vibesonic/internal/database/audio_features.go

package database

import (
	"database/sql"
	"encoding/json"

	"git.noroutes.net/NoRoutes/vibetunes/internal/audiofeatures"
)

// AudioFeaturesRow is one song's stored sonic-analysis result.
type AudioFeaturesRow struct {
	SongID       string
	TempoBPM     float64
	TempoValid   bool
	MusicalKey   string
	LoudnessLUFS float64
	Extra        audioFeaturesExtra
}

// audioFeaturesExtra is the analyzer output that doesn't have its own
// dedicated column — kept in extra_json so the schema doesn't need a
// migration every time the analyzer grows a new measurement.
type audioFeaturesExtra struct {
	SpectralCentroidHz float64     `json:"spectralCentroidHz"`
	SpectralRolloffHz  float64     `json:"spectralRolloffHz"`
	ZeroCrossingRate   float64     `json:"zeroCrossingRate"`
	Chroma             [12]float64 `json:"chroma"`
}

// Vector reconstructs the same fixed-length feature vector
// audiofeatures.Features.Vector produces, from stored values.
func (r AudioFeaturesRow) Vector() []float64 {
	tempo := 0.0
	if r.TempoValid {
		tempo = r.TempoBPM
	}
	v := make([]float64, 0, 17)
	v = append(v, tempo, r.LoudnessLUFS, r.Extra.SpectralCentroidHz, r.Extra.SpectralRolloffHz, r.Extra.ZeroCrossingRate)
	v = append(v, r.Extra.Chroma[:]...)
	return v
}

// UpsertAudioFeatures stores (or replaces) the analyzed features for a
// song.
func UpsertAudioFeatures(db *sql.DB, songID string, f *audiofeatures.Features) error {
	extra := audioFeaturesExtra{
		SpectralCentroidHz: f.SpectralCentroidHz,
		SpectralRolloffHz:  f.SpectralRolloffHz,
		ZeroCrossingRate:   f.ZeroCrossingRate,
		Chroma:             f.Chroma,
	}
	extraJSON, err := json.Marshal(extra)
	if err != nil {
		return err
	}
	var tempo sql.NullFloat64
	if f.TempoValid {
		tempo = sql.NullFloat64{Float64: f.TempoBPM, Valid: true}
	}
	_, err = db.Exec(`
		INSERT INTO audio_features (song_id, tempo_bpm, musical_key, loudness_lufs, extra_json, updated_at)
		VALUES (?, ?, ?, ?, ?, strftime('%Y-%m-%dT%H:%M:%fZ','now'))
		ON CONFLICT(song_id) DO UPDATE SET
			tempo_bpm = excluded.tempo_bpm,
			musical_key = excluded.musical_key,
			loudness_lufs = excluded.loudness_lufs,
			extra_json = excluded.extra_json,
			updated_at = excluded.updated_at`,
		songID, tempo, f.Key, f.LoudnessLUFS, string(extraJSON))
	return err
}

const audioFeaturesSelect = `SELECT song_id, tempo_bpm, musical_key, loudness_lufs, extra_json FROM audio_features`

func scanAudioFeaturesRow(scan func(dest ...any) error) (*AudioFeaturesRow, error) {
	var r AudioFeaturesRow
	var tempo sql.NullFloat64
	var loudness sql.NullFloat64
	var extraJSON string
	if err := scan(&r.SongID, &tempo, &r.MusicalKey, &loudness, &extraJSON); err != nil {
		return nil, err
	}
	r.TempoValid = tempo.Valid
	r.TempoBPM = tempo.Float64
	r.LoudnessLUFS = loudness.Float64
	_ = json.Unmarshal([]byte(extraJSON), &r.Extra)
	return &r, nil
}

// GetAudioFeatures returns a song's stored analysis, or nil if it
// hasn't been analyzed yet.
func GetAudioFeatures(db *sql.DB, songID string) (*AudioFeaturesRow, error) {
	row := db.QueryRow(audioFeaturesSelect+` WHERE song_id = ?`, songID)
	r, err := scanAudioFeaturesRow(row.Scan)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	return r, err
}

// ListAllAudioFeatures returns every analyzed song's features, the
// input the in-process sonic-similarity index is built from.
func ListAllAudioFeatures(db *sql.DB) ([]AudioFeaturesRow, error) {
	rows, err := db.Query(audioFeaturesSelect)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []AudioFeaturesRow
	for rows.Next() {
		r, err := scanAudioFeaturesRow(rows.Scan)
		if err != nil {
			return nil, err
		}
		out = append(out, *r)
	}
	return out, rows.Err()
}