V31_FEATURE_ENGINEERING_NOTES.md

V31 Feature Engineering Notes

Why we did V31

V16 is stable and strong, but it may saturate. V31 adds richer signal descriptors to capture information that plain MFCC/chroma stats can miss.

Goal:

• keep V16 baseline safety,
• add meaningful audio dynamics/rhythm/texture features,
• compare objectively against V16 before upload.

What was added in V31

1. MFCC Delta + Delta-Delta

   • Captures temporal changes in timbre.
   • Useful when genres differ by evolving patterns, not just static spectral shape.

2. HPSS (Harmonic-Percussive Source Separation)

   • Splits audio into harmonic and percussive components.
   • Helps distinguish melody-heavy vs beat-heavy genre characteristics.

3. Tempo / Beat Strength Features

   • Adds rhythmic cues (tempo, onset strength mean/std).
   • Useful for genre rhythm identity.

Where implemented

• Notebook: notebooks/DL_21f2000735_FINAL_UPLOAD_V31.ipynb
• Demo feature output script: src/v31_feature_demo_output.py
• Demo output file: reports/v31_demo_feature_output.json

How to use it in decisions

• Run V31 compare block (V16-base vs V31-fusion).
• Check:
  • v16_base_macro_f1
  • v31_fusion_macro_f1
  • delta_v31_minus_v16
• Upload V31 only if delta is non-negative and run is stable.

How to learn more

1. Librosa docs
   • MFCC / delta / HPSS / tempo APIs
2. Audio feature engineering guides
   • spectral contrast, rhythm features, pooling strategies
3. Ablation practice
   • turn one feature family on/off and record F1 delta
4. Error analysis loop
   • inspect confusion matrix and add features targeting weak class pairs

Practical next learning experiments

1. HPSS-only ablation vs base
2. Delta-only ablation vs base
3. Tempo-only ablation vs base
4. Combined (V31) vs V16 baseline
5. Class-wise F1 comparison for weak genres

This note exists to keep V31 explainable in viva and reproducible in future runs.