# Harmony Song Library: attribution and data notice

`harmony-song-library.json` is a teaching-oriented, normalized collection of
1,000 unique popular-song chord charts. It is not presented as one canonical
worldwide ranking of the “most successful” songs; no such single ranking
exists. The catalog combines chart-selected, critic-selected, and
expert-annotated collections and retains source/rank metadata where available.

## Sources and licenses

Licensing is source-specific; the combined teaching index does not replace or
merge the terms attached to each source collection.

- **McGill Billboard Project via CoCoPops** — original harmonic annotations by
  John Ashley Burgoyne, Jonathan Wild, and Ichiro Fujinaga; CoCoPops conversion
  by Claire Arthur and Nathaniel Condit-Schultz. The underlying McGill
  annotations are released under
  [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0/).
- **Rolling Stone Corpus via CoCoPops** — annotations by Trevor de Clercq and
  David Temperley; CoCoPops conversion by Claire Arthur and Nathaniel
  Condit-Schultz. Catalog data is used under
  [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
- **Isophonics via ChoCo** — Isophonics annotations by Matthias Mauch and
  collaborators; standardized in ChoCo by Andrea Poltronieri and
  collaborators. This ChoCo partition is released under
  [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
- **Modern hit charts from iReal Pro via ChoCo** — community-created iReal
  charts standardized by Andrea Poltronieri and collaborators in ChoCo, with
  canonical artist, title, and release-year metadata reviewed by the 80/20
  Music School. The 100-chart teaching selection uses the ChoCo standardized
  output under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/);
  upstream iReal charts are identified by ChoCo as public-domain material.

The current 1,000-song build contains 676 McGill Billboard records, 200
Rolling Stone Corpus records, 24 Isophonics records, and 100 reviewed modern
iReal/ChoCo records.

Direct source, repository, revision, creator, and license links are also stored
in the JSON payload's `sources` array. Chordify, JAAH, Mozart Piano Sonata, and
other non-commercial partitions are not used.

## Transformations

For this trainer, chord symbols are normalized to its supported chord
vocabulary, inversions are omitted, timed annotations are grouped into bars,
and exact duplicate section charts are condensed. The JSON contains chord and
formal-analysis facts only; it does not contain lyrics, melodies, or audio.

## Reproduction

With local CoCoPops and ChoCo checkouts, regenerate the file from the project
root with:

```sh
node scripts/generate-harmony-song-library.mjs \
  --cocopops /path/to/CoCoPops \
  --choco /path/to/choco
```