014e636889
- section-energy: track activity matrix + volume/velocity multipliers per section - smart-chords: ChordEngine with voice leading, inversions, 4 emotion modes - hook-melody: melody engine with hook/stabs/smooth styles, call-and-response - mix-calibration: Calibrator module (LUFS volumes, HPF/LPF, stereo, sends, master) - transitions-fx: FX track with risers/impacts/sweeps at section boundaries - sidechain: MIDI CC11 bass ducking on kick hits via DrumLoopAnalyzer - presets-pack: role-aware plugin presets (Serum/Decapitator/Omnisphere per role) Full SDD pipeline (propose→spec→design→tasks→apply→verify) for all 7 changes. 302/302 tests passing.
91 lines
4.8 KiB
Markdown
91 lines
4.8 KiB
Markdown
# Proposal: Section Energy Curve
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## Intent
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All 9 arrangement sections sound identical — full-band at static volume. Professional reggaeton builds energy across sections via sparse-to-dense track layering, velocity variation, and section-level volume riding. This change adds the missing dynamics.
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## Scope
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### In Scope
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- Centralized `TRACK_ACTIVITY` dict: which track roles play in which sections
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- `build_section_structure()` sets `velocity_mult` and `vol_mult` per section type
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- Unified `_section_active()` helper — single source of truth for section activity
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- All 7 track builders refactored to check centralized activity + apply `velocity_mult`
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- RPPBuilder extended to apply per-clip `vol_mult` (audio items get `D_VOL`, MIDI items get velocity scaling)
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- Rename `build` section to `pre-chorus` (professional reggaeton convention)
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- Update integration tests to match new section behavior
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### Out of Scope
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- Volume automation envelopes (REAPER `VOLENV2`) — deferred
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- Transition FX generation (risers, impacts, filtered sweeps)
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- Per-section filter automation (AutoFilter cutoff sweeps)
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- Section scene names in REAPER project — still flat arrangement
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## Capabilities
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### Modified Capabilities
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- `section-structure`: SectionDef `velocity_mult` and `vol_mult` now populated per section type instead of defaulting to 1.0
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- `track-generation`: All builders consume centralized activity matrix + section multipliers instead of ad-hoc section name checks
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### New Capabilities
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- `section-activity`: Centralized activity matrix defining which track roles are active per section type
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- `clip-volume`: ClipDef receives optional `vol_mult` field; RPPBuilder applies it to item `D_VOL` (audio) or velocity scaling (MIDI)
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## Approach
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**Principle**: Schema fields (`velocity_mult`, `vol_mult`) already exist in `SectionDef`. The bug is they're never populated or consumed. Add the wiring.
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1. **Activity matrix** — `TRACK_ACTIVITY` dict in compose.py maps `section_type → {role: bool}`. Section types: `intro`, `verse`, `pre-chorus`, `chorus`, `bridge`, `final`, `outro`.
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2. **Section multipliers** — `build_section_structure()` sets `velocity_mult` (controls note velocity) and `vol_mult` (controls clip gain) based on section type:
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| Section | velocity_mult | vol_mult |
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|---------|--------------|----------|
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| intro | 0.6 | 0.70 |
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| verse | 0.7 | 0.85 |
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| pre-chorus | 0.85 | 0.95 |
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| chorus | 1.0 | 1.00 |
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| bridge | 0.6 | 0.75 |
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| final | 1.0 | 1.00 |
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| outro | 0.4 | 0.60 |
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3. **Builder refactor** — Replace ad-hoc `if section.name in ("chorus","final")` with `_section_active(section, role, activity)` check. Multiply MIDI velocities by `section.velocity_mult`.
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4. **RPPBuilder** — `_build_item()` adds `D_VOL` for audio clips when `clip.vol_mult != 1.0`. MIDI clips already get velocity-scaled notes from step 3.
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5. **Section rename** — `build` → `pre-chorus` in `SECTIONS` and all references (`DRUMLOOP_ASSIGNMENTS`, builder filters). Existing section name "build" only appears in compose.py SECTIONS — no external consumers.
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## Affected Areas
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| Area | Impact | Description |
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|------|--------|-------------|
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| `scripts/compose.py` | Modified | Add `TRACK_ACTIVITY`, `_section_active()`, update `build_section_structure()`, refactor all 7 builders, rename build→pre-chorus |
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| `src/core/schema.py` | Modified | Add `vol_mult` field to `ClipDef` (optional, default 1.0) |
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| `src/reaper_builder/__init__.py` | Modified | `_build_item()` applies `D_VOL` from `clip.vol_mult` |
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| `tests/test_compose_integration.py` | Modified | Update section name references (build→pre-chorus), add activity matrix tests |
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| `tests/test_section_builder.py` | Modified | Add `velocity_mult`/`vol_mult` population tests |
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## Risks
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| Risk | Likelihood | Mitigation |
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|------|------------|------------|
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| RPP `D_VOL` not recognized by REAPER | Low | REAPER .rpp spec documents D_VOL on ITEM; test with actual REAPER load |
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| Section rename breaks test fixtures | Med | Grep all `.py` for "build" section name; CI catches breakage |
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| Activity matrix too strict — creative users want full band in bridge | Low | Activity matrix is a constant at file top — easy to edit; could be CLI flag later |
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## Rollback Plan
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Revert commit. No schema migrations needed — `vol_mult` on ClipDef defaults to 1.0 (zero behavioral change if not set). Section rename is cosmetic in output RPP.
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## Dependencies
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None — no new packages, no external APIs.
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## Success Criteria
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- [ ] All sections sound audibly different (sparse intro → dense chorus)
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- [ ] Drums + pad only in intro (no bass, no lead, no chords)
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- [ ] Full band in chorus (all 7 tracks active)
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- [ ] Velocity differences between verse (soft) and chorus (hard)
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- [ ] 110 existing tests still pass
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- [ ] `.rpp` output opens in REAPER without errors
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