# Phase 1F: Tempogram Pivot - Documentation Alignment (Post-Sprint)
**Date**: 2025-12-17
**Status**: ✅ Documentation Updated and Aligned
**Implementation Status**: ⚠️ Implemented; tuning/validation in progress (baseline stable)
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## Summary
This sprint included significant implementation + experimentation around Phase 1F tuning, validation tooling, onset consensus wiring, and BPM fusion/legacy A/B modes. This document records the **documentation alignment** work performed afterward so the project remains readable and traceable.
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## Current Status (Post-Sprint)
Phase 1F is implemented and integrated. Validation tooling has been expanded (A/B modes, ablation toggles, multi-file analysis). Accuracy remains **below target**, but the baseline is stable and fully reproducible.
**See**:
- `docs/progress-reports/PHASE_1F_VALIDATION.md` (run history + current baseline + failure modes)
- `docs/progress-reports/PHASE_1F_LITERATURE_REVIEW.md` (Phase 1F literature review)
- `PIPELINE.md` (authoritative end-to-end pipeline + decision points)
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## Documentation Updates (this sprint)
### 1) Authoritative pipeline reference
- ✅ `PIPELINE.md`
- Updated to reflect current runtime wiring and decision points
- Includes debugging/log guidance
### 2) Validation workflow documentation
- ✅ `validation/README.md`
- Updated to document current validation flags and analysis scripts
### 3) Phase 1F progress reports updated
- ✅ `PHASE_1F_VALIDATION.md`
- Updated run history and baseline results
- Includes A/B modes used during tuning
- ✅ `PHASE_1F_COMPLETE.md`
- Updated to include post-implementation wiring & tooling changes
### 4) Root docs alignment
- ✅ `README.md`, `ROADMAP.md`, `DEVELOPMENT.md`, `CHANGELOG.md`
- Updated references and tooling details so readers can reproduce the current state
### 5. Project README
- ✅ `README.md` - Project status
- Updated features section
- Updated status section
- Updated roadmap section
- Added deprecation notes
### 6. Summary Document
- ✅ `TEMPOGRAM_PIVOT_SUMMARY.md` - Cross-reference
- Updated implementation plan
- Added deprecation timeline
- Updated file structure
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## Implementation Strategy
### Dual Tempogram Approach
**Phase 2A: Autocorrelation Tempogram**
- Test each BPM hypothesis (40-240, 0.5 BPM resolution)
- Direct periodicity testing
- Expected: 75-85% accuracy, 20-40ms
**Phase 2B: FFT Tempogram**
- FFT the novelty curve
- Convert frequencies to BPM
- Expected: 75-85% accuracy, 10-20ms
**Phase 2C: Comparison & Selection**
- Run both methods
- Compare results
- Use best or ensemble
- Expected: 85-92% accuracy, 30-60ms
### Hybrid Approach (Future)
Documented for future implementation:
- FFT: Fast coarse estimate (2 BPM resolution)
- Autocorr: Precise fine estimate (±5 BPM around FFT, 0.5 BPM resolution)
- Benefits: Speed + Precision
- Status: Documented, not implemented yet
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## Deprecation Plan
### Old Methods (Phase 1B)
**Files to Deprecate**:
- `src/features/period/autocorrelation.rs`
- `src/features/period/comb_filter.rs`
- `src/features/period/candidate_filter.rs`
**Timeline**:
1. **Phase 1F**: Keep active for A/B comparison
2. **After Validation**: Mark as `#[deprecated]`
3. **v0.9.2**: Remove entirely
**Rationale**: Old methods are fundamentally broken (30% accuracy). Once tempogram is validated, no reason to keep them.
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## File Structure
### New Files (To Be Created)
- `src/features/period/novelty.rs` - Novelty curve extraction
- `src/features/period/tempogram_autocorr.rs` - Autocorrelation tempogram
- `src/features/period/tempogram_fft.rs` - FFT tempogram
- `src/features/period/tempogram.rs` - Main entry point (comparison)
- `src/features/period/multi_resolution.rs` - Multi-resolution validation
### Files to Update
- `src/features/period/mod.rs` - Add tempogram methods
- `src/lib.rs` - Update pipeline
### Files to Deprecate (After Validation)
- `src/features/period/autocorrelation.rs`
- `src/features/period/comb_filter.rs`
- `src/features/period/candidate_filter.rs`
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## Expected Results
| Accuracy (±2 BPM) | ~20% | 70-80% | 80%+ |
| Accuracy (±5 BPM) | 30% | 75-85% | 85-92% |
| Subharmonic Errors | 10-15% | 2-3% | <1% |
| MAE | 34 BPM | 4-6 BPM | 3-4 BPM |
| Speed | 15-45ms | 20-40ms | 30-60ms |
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## Implementation Timeline
- **Phase 1**: Novelty curve (20 min)
- **Phase 2A**: Autocorrelation tempogram (40 min)
- **Phase 2B**: FFT tempogram (30 min)
- **Phase 2C**: Comparison & selection (20 min)
- **Phase 3**: Hybrid approach documented (5 min)
- **Phase 4**: Multi-resolution (20 min)
- **Phase 5**: Integration (20 min)
- **Phase 6**: Testing & validation (40 min)
**Total: 3-4 hours**
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## Consistency Verification
### ✅ All Documentation Aligned
- **Accuracy Claims**: 30% → 85-92% (consistent)
- **Timeline**: 3-4 hours (consistent)
- **Methods**: Both FFT and autocorr (consistent)
- **Deprecation**: Plan documented (consistent)
- **Hybrid**: Documented for future (consistent)
### ✅ Cross-References Verified
- ROADMAP → EVALUATION ✓
- DEVELOPMENT → EVALUATION ✓
- README → All docs ✓
- EVALUATION → HYBRID ✓
- SUMMARY → All docs ✓
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## Next Steps
Documentation work is caught up. Next engineering effort should focus on:
- Improving Phase 1F metrical-level / harmonic-family selection without regressions
- Expanding validation beyond a single small batch (multiple batches, aggregate metrics)
- Keeping A/B modes (legacy-only, ablations) for regression testing until Phase 1F is validated
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**Status**: ✅ **ALL DOCUMENTATION COMPLETE AND ALIGNED**
**Ready for Implementation**: Yes
**Recommendation**: Proceed with dual tempogram implementation following the technical specification.
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**Last Updated**: 2025-01-XX
**Next Action**: Begin Phase 1 implementation (Novelty curve)