Stem Cache¶

Demucs stem separation is slow on CPU (5–15 min for a 40-min file). The stem cache ensures it only runs once per file.

How the cache key works¶

flowchart LR
    A[Input file] --> B[Read first 8 MiB]
    B --> C[SHA-256 hash]
    C --> D[First 16 hex chars]
    D --> E["~/.praisonai/editor/.demix_cache/{hash}/"]
    E --> F{vocals.wav + no_vocals.wav\nboth exist?}
    F -->|Yes| G[✅ Reuse — skip Demucs]
    F -->|No| H[Run Demucs → save]

Cache location¶

~/.praisonai/editor/.demix_cache/
  └── a78a770eb2572ef6/
        ├── vocals.wav      (424 MB)
        └── no_vocals.wav   (424 MB)

Timing example¶

Clear the cache¶

rm -rf ~/.praisonai/editor/.demix_cache/

Python check¶

from praisonai_editor._demix import has_demucs, isolate_vocals
print(has_demucs())  # True / False