Importing a Demucs-compatible Model

Stem Splitter pulls a song apart into stems (drums, bass, vocals and so on) right on your own computer. It needs a Demucs-compatible model file to do that, and you supply the file yourself. No model weights ship with the app, and the app never downloads, hosts, sells, recommends or bundles them. That keeps the tool simple, and it keeps the licensing of any model file in your hands.

This guide covers how to import a compatible model and which model types the app can load.

What “user-supplied” means

The first time you open Stem Splitter it asks you to import a model file. You obtain that file yourself from a source you trust, and the app verifies and installs your copy. Everything after that runs locally: nothing about your audio or your model is uploaded anywhere.

Third-party model weights are not included, hosted, sold, recommended or downloaded by this app. Compatibility only means the app may be able to load the file. Review the model’s own licence before you use it.

How to set up a model

1. Obtain a compatible model file (see the compatibility table below) from a source you trust.
2. Review that model’s own licence and make sure you have the right to use it.
3. In Stem Splitter, tick the confirmation and choose Import Model, then select the file.
4. The app checks the file and installs it. Once it says the model is installed you are ready to split a song.

Models live in one slot per stem count: a 4-stem slot and a 6-stem slot. Importing a new 4-stem model replaces whatever was in the 4-stem slot, so “loading a new version” is just importing over the top. You can remove an installed model at any time from the model list.

Tested compatible model types

The table lists model families as compatibility targets. It is not a download list, not a ranking and not a recommendation. The app identifies a file by its format, not by where it came from.

Model family	Stems	Runs today	Licence
HTDemucs (htdemucs)	4	Yes	User must verify
6-source HTDemucs (htdemucs_6s)	6	Yes	User must verify
Demucs v3 (hdemucs_mmi)	4	Recognised, declined	User must verify

The 4-stem and 6-stem HTDemucs models run today. A Demucs v3 model (hdemucs_mmi) is recognised but needs a separate runner that is not shipped yet, so the app declines it rather than pretend to run it.

Models from other engines (MDX-Net, UVR, Spleeter) are a different format and are not supported.

Supported file format

Stem Splitter loads Demucs-compatible ggml .bin model files. The app auto-detects the model from the file itself: it reads the header, checks the file is a complete, intact model and works out how many stems it produces. A file that is not a recognised Demucs model, or one that is truncated or corrupt, is rejected with a clear message rather than installed.

Troubleshooting

• “This is not a recognised model file”: the file is not a Demucs ggml model, or it is a model from a different engine (MDX, UVR, Spleeter). Check you selected the right .bin file.
• “This model file looks incomplete or corrupt”: the download or copy did not finish, or the file was damaged. Obtain a fresh copy and import it again.
• “This is a Demucs v3 model”: the file is recognised but the app can only run 4-stem and 6-stem HTDemucs models at the moment. Support for more model types is planned.
• Not enough disk space: the model needs room to install. Free up some space and try again.

Where separation runs

On your own machine, start to finish. Splitting a track usually takes a few minutes depending on its length and your computer. Stem Splitter is built for sampling, not mastering, so results vary by track. When separation finishes you can preview each stem, then save the ones you want to your sample library or export them, ready to chop and load onto your EP.