AI tasks
Split a song into stems
Separate a mix into vocals, drums, bass and everything else: how it works, where it leaks, and what to make with the parts.
Stem separation takes a finished mix and gives you back four aligned parts: vocals, drums, bass and other. Mute the vocal for a karaoke track, loop the drums under a new bass line, or sample one instrument that was never recorded on its own.
Try it
Open StemSep, choose a song or an example, pick a model and press Split stems. Solo each stem, then export them as WAV files that stay lined up with the original.
How it works
A trained model has listened to many songs alongside their original multitrack recordings. Given a new mix, it estimates which parts of the sound belong to each instrument and builds a mask for each one. The four stems add back up to roughly the original. Stem separation in Learn walks through the technique.
StemSep offers methods that run in different places:
| Method | Where it runs | Your audio |
|---|---|---|
| On this device | In your browser, after a one-time model download | Stays on your computer |
| Maru server | On Maru's servers | Uploaded for processing |
| Commercial provider | On a separation service, with your own key | Uploaded to that provider |
Ideas
- Practise with the band. Remove your instrument from a song and play along.
- Remix and mash up. Put one song's vocal over another's drums; see Stems to remix.
- Sample cleanly. Pull a drum break or a bass phrase out of a mix before you chop it.
- Transcribe better. Separate first, then turn the bass stem into MIDI.
- Find the groove. Track beats on the drum stem rather than the full mix; see Follow the beat.
What it gets wrong
- Leakage. A little hi-hat in the vocal stem, a little vocal in "other". Soloed stems reveal it; in a mix it often disappears.
- Artefacts. Reverb tails, distorted guitars and dense mixes produce watery or phasey sounds.
- Four buckets only. Piano, guitar, strings and synths all land in "other".
- Rights do not change. A separated vocal is still the original artist's recording. Check what you are allowed to release.
- Songs can be up to 3 minutes and 128 MiB.
Build your own
Remix StemSep in Studio, or ask your coding agent to build on it:
Read the Maru docs page "Separate stems in a module", then read StemSep's source with `maru module files stemsep` and `maru module read stemsep src/index.ts`. Build a practice tool that separates a song, mutes the instrument I choose, and loops a section I mark so I can play along.
Developers can start from Separate stems in a module. The model directory compares separation models.