Free open-source tool: turn MP3 folders into Traktor stem files (.stem.mp4), Windows

DJ Software & Apps Traktor
1

Hi all,

I built a small free tool for Windows and thought it might help some of you: StemMaker.

It turns MP3s, or whole folders of them, into real stem files (.stem.mp4: master plus drums, bass, other and vocals). The separation is Demucs, compiled as C++, so there’s nothing to install besides the tool itself: no Python, no PyTorch, no CUDA. It runs offline, needs no account and is MIT licensed.

  • Whole folders in a queue, overnight, with resume after a crash. Tags and cover art are copied.
  • A small built-in player to check every file without any DJ software (mute, solo and a fader per stem, A/B against the original).
  • The files work in Traktor Pro 3 and 4 and on Kontrol hardware with stem decks.

To be fair about where it fits: Traktor Pro 4 separates stems itself and is faster per track. StemMaker is for when you want portable stem files next to your music, want to convert whole folders at once, use Traktor 3, or don’t have Traktor at all. Separation quality is about on par with Traktor 4 in my own comparison.

It’s CPU only right now. A faster engine is in the works and will come as a free update.

Demo video and download: GitHub - Elospeed/StemMaker: Free Windows tool that turns MP3s into Traktor stem files (.stem.mp4) – no Python, no setup. · GitHub

Feedback welcome, especially if something doesn’t work on your setup.

2

Update: StemMaker 2.0 is out. New is a Turbo engine (ONNX Runtime + DirectML): with a graphics card a song minute takes about 3 seconds on an RTX 4060 Ti. Without a suitable card it runs on the CPU, roughly 30 to 110 seconds per song minute depending on the PC. A short pre-test picks the faster option by itself. Input now also includes FLAC, WAV and more, and the files also load in the Mixxx 2.6 beta.

StemMaker 2.0:

stemmaker-en
stemmaker-en1720×1448 75.1 KB

Built-in player (StemPlayer):

stemplayer-loop-en
stemplayer-loop-en820×830 32.8 KB

Download: Release StemMaker 2.0 · Elospeed/StemMaker · GitHub

3

Awesome, going to check this out! Does it maintain the quality if .wav or .flac are used?

4

Thanks! Yes: WAV and FLAC work directly. By default, lossless sources get AAC at 320 kbit/s, the highest setting. If you want it fully lossless, set the audio format to ALAC, the stem file just gets a lot bigger. The separation itself always runs at 44.1 kHz.