/**
 * Chroma features from a log-frequency spectrum (formerly "CQT chroma").
 * Delegates to logFrequencySpectrum + foldLogSpectrumToChroma.
 * @param {Float32Array} y - Audio time series
 * @param {number} sr - Sample rate
 * @param {number} hop_length - Hop between frames
 * @param {number|null} fmin - Minimum frequency (C1 = 32.7 Hz if null)
 * @param {number} n_chroma - Number of chroma bins
 * @param {number} tuning - Tuning deviation in cents
 * @param {number} n_octaves - Number of octaves to analyze
 * @param {number} bins_per_octave - Must equal n_chroma (fold constraint)
 * @returns {Array<Float32Array>} [n_chroma][n_frames]
 */
export function chroma_cqt(y: Float32Array, sr?: number, hop_length?: number, fmin?: number | null, n_chroma?: number, tuning?: number, n_octaves?: number, bins_per_octave?: number): Array<Float32Array>;
/**
 * Chromagram from STFT — now via feature/chroma.js
 * (Gaussian filterbank matmul + per-frame inf-norm; the old version used
 * hard nearest-semitone binning and no frame centering).
 * @param {Float32Array} y - Audio time series
 * @param {number} sr - Sample rate
 * @param {number} hop_length - Hop length
 * @param {number} n_fft - FFT window size
 * @param {number} n_chroma - Number of chroma bins
 * @param {number|null} tuning - Tuning in fractional chroma bins
 *   (0.0 default preserves this shim's historical signature; pass null to
 *   estimate from the signal)
 * @returns {Array<Float64Array>} [n_chroma][n_frames]
 */
export function chroma_stft(y: Float32Array, sr?: number, hop_length?: number, n_fft?: number, n_chroma?: number, tuning?: number | null): Array<Float64Array>;
/**
 * DEPRECATED NAME — this is NOT a constant-Q transform. Delegates to
 * feature/chroma.js logFrequencySpectrum (nearest-FFT-bin sampling at
 * log-spaced frequencies).
 * @returns {Array<Float32Array>} time-major [n_frames][n_bins]
 */
export function constant_q_transform(y: any, sr: any, hop_length: any, fmin?: any, n_bins?: number, tuning?: number): Array<Float32Array>;
/**
 * Map an interleaved FFT spectrum ([re0, im0, re1, im1, ...]) to
 * log-frequency bins by nearest-bin sampling (legacy helper for the
 * xa-onset.fft output format).
 * @param {Float32Array} spectrum - Interleaved complex FFT output
 * @param {number} sr - Sample rate
 * @param {number} fmin - Minimum frequency
 * @param {number} n_bins - Number of log-frequency bins
 * @param {number} n_fft - FFT size
 * @returns {Float32Array} log-frequency magnitude bins
 */
export function mapToCQTBins(spectrum: Float32Array, sr: number, fmin: number, n_bins: number, n_fft: number): Float32Array;
/**
 * Fold a time-major log-frequency spectrum into chroma classes.
 * Delegates to feature/chroma.js foldLogSpectrumToChroma, which (unlike the
 * old silent version) throws when bins_per_octave !== n_chroma.
 * @returns {Array<Float32Array>} [n_chroma][n_frames]
 */
export function cqt_to_chroma(cqt: any, n_chroma?: number, bins_per_octave?: number): Array<Float32Array>;
/**
 * FAST VARIANT (not the reference path): fold magnitude spectra into chroma by
 * hard nearest-semitone binning with sqrt-energy-share normalization.
 * Kept as an explicitly-named approximation; feature/chroma.js chroma_stft
 * is the reference path.
 * @param {Array} magnitude_spectra - time-major magnitude spectra
 * @param {number} sr - Sample rate
 * @param {number} n_fft - FFT size
 * @param {number} n_chroma - Number of chroma bins
 * @param {number} tuning - Tuning deviation in cents
 * @returns {Array<Float32Array>} [n_chroma][n_frames]
 */
export function stft_to_chroma(magnitude_spectra: any[], sr: number, n_fft: number, n_chroma?: number, tuning?: number): Array<Float32Array>;
/**
 * Convert frequency to chroma class (0-11)
 * @param {number} freq - Frequency in Hz
 * @returns {number} Chroma class (0=C, 1=C#, 2=D, etc.)
 */
export function freq_to_chroma(freq: number): number;
/**
 * Compute chroma vector from a single spectrum (fast variant, not reference)
 * @param {Float32Array} spectrum - Magnitude spectrum
 * @param {number} sr - Sample rate
 * @param {number} tuning - Tuning deviation
 * @returns {Float32Array} Chroma vector (12 elements)
 */
export function spectrum_to_chroma(spectrum: Float32Array, sr: number, tuning?: number): Float32Array;
/**
 * Enhance chroma features for better key detection
 * @param {Array} chroma - Input chroma matrix
 * @param {number} norm - Normalization order (1, 2, or Infinity)
 * @returns {Array} Enhanced chroma matrix
 */
export function enhance_chroma(chroma: any[], norm?: number): any[];
/**
 * Compute chroma energy (sum of all chroma values per frame)
 * @param {Array} chroma - Chroma matrix
 * @returns {Float32Array} Energy per frame
 */
export function chroma_energy(chroma: any[]): Float32Array;
/**
 * Convert chroma index to note name
 * @param {number} chroma_idx - Chroma index (0-11)
 * @returns {string} Note name
 */
export function chroma_to_note(chroma_idx: number): string;
/**
 * Compute a Variable-Q chromagram
 * @param {Float32Array|null} y - Audio time series
 * @param {number} sr - Sample rate
 * @param {Array|null} V - Pre-computed VQT spectrogram
 * @param {number} hop_length - Hop length
 * @param {number|null} fmin - Minimum frequency (default: C1)
 * @param {string|Array} intervals - Interval specification (default: 'equal')
 * @param {number|null} norm - Normalization (default: np.inf)
 * @param {number} threshold - Threshold for chroma calculation
 * @param {number} n_octaves - Number of octaves
 * @param {number} bins_per_octave - Bins per octave
 * @param {number} gamma - Bandwidth offset for VQT (0 for CQT)
 * @returns {Array} Chroma features [12 x n_frames]
 */
export function chroma_vqt(y?: Float32Array | null, sr?: number, V?: any[] | null, hop_length?: number, fmin?: number | null, intervals?: string | any[], norm?: number | null, threshold?: number, n_octaves?: number, bins_per_octave?: number, gamma?: number): any[];
export const NOTE_NAMES: string[];