# Procedural Instrument Synthesis

> Generate instrument samples for ZX game music. **Spec-Driven Workflow (RECOMMENDED):** 1. Create `.spec.py` in `.studio/specs/instruments/` 2. Run `python .studio/generate.py --only instruments` **Load references when:** - Instrument specs → `procedural-sounds/references/sound-spec-format.md` - Example specs → `examples/bass.spec.py`, `examples/lead.spec.py` - Karplus-Strong → `references/karplus-strong.md` - FM synthesis → `references/fm-synthesis.md` - Drum examples → `references/drum-examples.py` **Before generating:** Check `.studio/sonic-identity.md` for audio specs.

- Skill: `majiayu000/procedural-instrument-synthesis` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/procedural-instrument-synthesis`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/procedural-instrument-synthesis/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/procedural-instrument-synthesis

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# Procedural Instrument Synthesis

Generate production-quality instrument samples using a **spec-driven workflow**.

## Spec-Driven Workflow

**Step 1: Create Spec**
```python
# .studio/specs/instruments/bass.spec.py
INSTRUMENT = {
    "instrument": {
        "name": "bass",
        "base_note": "C2",
        "synthesis": {
            "type": "karplus_strong",
            "damping": 0.994,
            "brightness": 0.5
        },
        "envelope": {"attack": 0.01, "decay": 0.4, "sustain": 0.3, "release": 0.3},
        "output": {"duration": 1.5, "bit_depth": 16, "loop": True}
    }
}
```

**Step 2: Run Generator**
```bash
python .studio/generate.py --only instruments
```

See `procedural-sounds/references/sound-spec-format.md` for complete format.

## Technique Selection

| Instrument | Technique | Reference |
|------------|-----------|-----------|
| Acoustic Guitar | Karplus-Strong | `karplus-strong.md` |
| Electric Piano | FM Synthesis | `fm-synthesis.md` |
| Bells | FM (inharmonic) | `fm-synthesis.md` |
| Organ | Additive | `additive-synthesis.md` |
| Strings/Pads | Wavetable | `wavetable-synthesis.md` |
| Synth Lead/Bass | Subtractive | `subtractive-synthesis.md` |
| Drums | See examples | `drum-examples.py` |

## Why Basic Synthesis Sounds Chiptuney

| Problem | Why It Sounds Bad |
|---------|-------------------|
| Raw `np.sin()` | Static timbre, no evolution |
| Simple ADSR | Real instruments have complex envelopes |
| Instant attack | Real instruments have transients |
| Single oscillator | Real instruments have multiple components |

## Quality Checklist

- No clicks (attack/release ramps)
- Pitch correct (verify frequency)
- Timbre evolves (envelope on filter/index)
- Attack has character (transient noise)
- Sounds musical (test in context)

## Related Skills

- `procedural-sounds` - SFX synthesis
- `sound-design/sonic-style-language` - Audio style specs
- `tracker-music/xm-format` - XM writer