- name
- music-seperator-demucs
- description
- Separate vocals and instrument stems from audio files with Demucs CLI. Use when the user asks for vocal extraction, accompaniment generation, stem splitting, batch separation, output format conversion (wav/flac/mp3), or Demucs performance/memory tuning on CPU/GPU. Also trigger when the user mentions demucs or demucas.
- homepage
- https://github.com/facebookresearch/demucs
- metadata
- {"clawdbot":{"emoji":"🎚️","requires":{"bins":["demucs"]},"install":[{"id":"pip","kind":"python","package":"demucs","bins":["demucs"],"label":"Install Demucs (pip)"}]}}
Demucs
Use demucs to split music into stems (default: vocals, drums, bass, other).
Quick start
- Help:
demucs --help - Basic split:
demucs "input.mp3" - Output dir:
demucs "input.mp3" -o "D:\\output" - Vocals only pair:
demucs "input.mp3" --two-stems vocals
Prerequisites
- Demucs available:
demucs --helpor absolute path likeD:\demucs-agent-tool\venv\Scripts\demucs.exe --help. - FFmpeg available:
ffmpeg -versionmust succeed. - Note:
ffmpeg-pythonis only a Python wrapper and does not installffmpeg.exe.
Common options
- Model:
-n htdemucs(default) or other installed model names. - Device:
-d cudaor-d cpu. - Chunking:
--segment 8 --overlap 0.25to reduce VRAM/RAM pressure. - No chunking:
--no-splitfor short audio with enough memory. - Equivariant shifts:
--shifts 1..10(higher quality, slower). - Parallel jobs:
-j 2(or more on strong CPUs).
Output format
- Default output is WAV.
- FLAC:
demucs "input.mp3" --flac - MP3:
demucs "input.mp3" --mp3 --mp3-bitrate 320 --mp3-preset 2 - Safer clipping behavior:
--clip-mode rescale(default) or--clip-mode clamp.
Naming and folder layout
- Default output path pattern:
separated/<model>/<track>/<stem>.<ext>. - Customize names:
--filename "{track}/{stem}.{ext}". - Variables supported:
{track},{trackext},{stem},{ext}.
Batch usage
- Multiple files in one call:
demucs "a.mp3" "b.wav" "c.flac" -o "D:\\separated". - Prefer absolute paths for automation scripts and scheduled jobs.
Windows notes
- In venv, executable is usually
venv\\Scripts\\demucs.exe. - Use quoted paths when spaces exist:
demucs "D:\\My Music\\song.mp3". - For external programs, prefer absolute executable path instead of shell activation.
- If non-ASCII paths cause tool/runtime issues, copy input to a temporary ASCII path and run Demucs there.
Troubleshooting
demucsnot found: runpython -m demucs --helpor callvenv\\Scripts\\demucs.exedirectly.FFmpeg is not installed/ffprobe not found: install FFmpeg and add it to PATH, then verify withffmpeg -version.- Out of memory: lower
--segment(for example6or4), set-d cpu, or process fewer tracks at once. - Slow speed on CPU: reduce
--shifts, keep chunking enabled, and tune-j. - Install/network failures: use a stable mirror and longer timeout when running pip.