nodruma

No Drama Drums — portable C++/WASM tool to chop drum grooves and recreate synth kick / snare / hats

NoDruma breaks samples into chops and regenerates a clean synthetic drum sound clones

WASM Webapp features

• Drum Chopper + Auto Recreate w/ Drum Synth
• Sample Chopper + Sample Mapping
• Pitch, EQ Controls
• MIDI Controls
• Export Samples as Kit

Build

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j
ctest --test-dir build --output-on-failure

Binary: ./build/nodruma

./build/nodruma help
./build/nodruma help split

Live demo (WASM)

Browser MPC kit builder under webapp/: left = drum split / classify / recreate (pads 1–9, MIDI C2–G♯2); right = QWERTY sample chopper (MIDI C3+). Decode at 44.1 kHz; crop a slice before process. Header Looper stacks pad takes into independent loop tracks (survives kit Reset). Session autosaves to IndexedDB until Clear session. Export drums or chops as ZIP.

./webapp/scripts/build_wasm.sh
python3 -m http.server 8080 -d webapp

GitHub Pages deploys from main via .github/workflows/pages.yml (enable Pages → GitHub Actions in repo settings).

What works today

Feature	Status
Groove chop (split) via spectral flux	Good on typical breaks
Classify kick / snare / hat	Improved (onset-aligned sub/LF/HF); duplicates still common
Recreate snare from chop	Strong (layer mix)
Recreate hat from chop	Decent on short hats
Recreate kick from one-shot / mix	Usable; still improving
Morph params from session cache	Kick-oriented

Generated files go under ./output/ (gitignored).

Tester recipes

1. Split a groove and recreate hits

mkdir -p output
./build/nodruma split \
  --in your_groove.wav \
  --out-dir output/split/demo \
  --extract

Then listen to:

• output/split/demo/00N_*.wav — raw chops
• output/split/demo/extracted/00N_*_nodruma.wav — recreated
• output/split/demo/hits.json — onset / kind / confidence

2. Rebuild a single one-shot

./build/nodruma process --model snare --in snare_chop.wav --out output/snare_out.wav
./build/nodruma process --model kick  --in kick.wav       --out output/kick_out.wav \
  --dump-layers output/layers/kick

3. Kick morph (analyze once, tweak gains)

./build/nodruma process --model kick --in kick.wav \
  --out output/kick_out.wav --write-session output/kick.bin
./build/nodruma morph --session output/kick.bin --model kick --out output/kick_morph.wav

Commands (short)

Command	Purpose
process	Analyze + resynthesize one WAV
split	Chop groove → WAVs + optional --extract
detect	Kick-oriented onset dump
morph	Resynth from session cache
info / version / help	Meta

Full flag lists: nodruma help <command> or docs/USAGE.md.

Docs

• docs/USAGE.md — tester guide, flags, tips
• docs/ARCHITECTURE.md — DSP pipeline

Layout

• include/nodruma/ — public C++ / C API
• src/core/ — FFT, onset, split, STFT, extract, synth, engine
• src/models/ — kick / snare / hat
• tools/nodruma_cli/ — CLI
• webapp/ — WASM MPC demo (GitHub Pages)
• tests/ — unit tests
• output/ — local generations (gitignored)

License

Released under the Apache 2.0 license.