import type { BandMeasurement, BandProfile } from "./measure.js";
/**
 * Interpretation of measured band statistics. Pure functions only — no FFmpeg,
 * no I/O — so every threshold here is unit-testable and reviewable.
 *
 * Two ideas carry the whole model:
 *
 * 1. A band's *spread* (p90 - p10 of its window RMS) says whether the band
 *    carries music or noise. Music moves with the performance; a hiss or rumble
 *    floor sits still. Level alone cannot tell those apart.
 *
 * 2. The noise floor can only be *observed* where the performance stops. Over a
 *    continuous performance, even the lowest percentile measures the quietest
 *    music, not the noise — so an estimate taken there is an upper bound and is
 *    marked low-confidence, and callers must denoise conservatively.
 */
/** Spread at or below this is a stationary floor rather than performance. */
export declare const STATIONARY_SPREAD_DB = 6;
/** Spread at or above this clearly tracks a performance. */
export declare const DYNAMIC_SPREAD_DB = 9;
/** This far below the music core, a band cannot be heard. */
export declare const EMPTY_RELATIVE_DB = -60;
/** Below this absolute level there is nothing to preserve or remove. */
export declare const EMPTY_ABSOLUTE_DB = -95;
/**
 * How far a band must tower over the median band to read as a sustained tone
 * rather than part of a flat noise bed. Flat noise stays within ~10 dB of the
 * median; a held note is tens of dB above it.
 */
export declare const TONE_PROMINENCE_DB = 20;
export type BandContent = "signal" | "noise" | "empty";
export type NoiseFloorSource = "gap" | "hiss-band" | "quietest-window" | "none";
/**
 * Confidence granted to a floor extrapolated from the hiss region.
 * Lower than a floor observed in a gap, far higher than a full-mix percentile.
 */
export declare const HISS_BAND_CONFIDENCE = 0.55;
/**
 * Correction applied to the hiss-band extrapolation, in dB.
 *
 * Crossover band edges are nominal, so the effective width of each band is wider
 * than `highHz - lowHz` and the extrapolation reads low. Measured against
 * synthetic hiss at -40, -50 and -60 dBFS the shortfall was a consistent
 * 3.4-3.5 dB, independent of level, so it is corrected here — leaving
 * `noiseFloorDb` an unbiased estimate of the noise's broadband RMS.
 */
export declare const HISS_EXTRAPOLATION_CALIBRATION_DB = 3.5;
/**
 * Broadband noise level extrapolated from the bands that hold only noise.
 *
 * A full-mix percentile cannot find the floor of a continuous performance: its
 * quietest window is still music, which overestimates the floor by 20-30 dB on
 * real material. Above the content, though, there is nothing *but* noise, and
 * broadband hiss is roughly flat — so its level there scales up to a broadband
 * figure by the ratio of bandwidths.
 *
 * Only bands above `fromHz` are used. Rumble is also stationary noise but is
 * concentrated at the bottom, and extrapolating from it would overestimate the
 * broadband level enormously.
 */
export declare function noiseFloorFromHissBands(bands: BandVerdict[], nyquistHz: number | null, fromHz?: number): number | null;
export interface BandVerdict {
    lowHz: number;
    highHz: number;
    centerHz: number;
    /** Typical level of the band (p50 of window RMS, dBFS). */
    levelDb: number | null;
    /** Level the band falls back to, dBFS — measured in a gap when one exists. */
    floorDb: number | null;
    spreadDb: number | null;
    content: BandContent;
    /** 0–1, how stationary the band is. */
    stationarity: number | null;
}
export interface NoiseModel {
    /** Best estimate of the broadband noise level, dBFS. */
    noiseFloorDb: number | null;
    /** 0–1. Only a real gap in the performance earns a high value. */
    noiseFloorConfidence: number;
    noiseFloorSource: NoiseFloorSource;
    /** Loud-to-quiet span of the mix, dB. A real signal-to-noise estimate. */
    snrDb: number | null;
    /** p50 of the loudest band — the level the music core sits at. */
    musicReferenceDb: number | null;
    /** Highest frequency still carrying performance, Hz. */
    bandwidthHz: number | null;
    /** Level of stationary high-frequency noise relative to the music core, dB. */
    hissRelativeDb: number | null;
    /** Level of stationary low-frequency noise relative to the music core, dB. */
    rumbleRelativeDb: number | null;
    /** How stationary the overall noise floor is, 0–1. */
    stationarity: number | null;
    bands: BandVerdict[];
}
/** 1 when the band sits perfectly still, 0 once it moves like a performance. */
export declare function stationarityOf(spreadDb: number | null): number | null;
/**
 * Decide whether a band carries performance, a stationary noise floor, or nothing.
 *
 * Spread decides first; level only separates "quiet noise" from "silence".
 * `fileIsDynamic` guards the level-based escape hatch: in a file that never
 * moves at all (pure tone, pure noise) loudness is no evidence of performance.
 */
export declare function classifyBandContent(band: Pick<BandMeasurement, "p50" | "spreadDb">, musicReferenceDb: number | null, fileIsDynamic?: boolean, 
/**
 * Median band level. In a file that never moves, a band towering over the
 * median is a sustained tone (content), while flat noise sits close to it.
 */
medianBandDb?: number | null): BandContent;
export interface NoiseModelInput {
    /** Whole-file band profile. */
    profile: BandProfile;
    nyquistHz: number | null;
    /**
     * Band profile measured inside a gap in the performance — a true noise print.
     * When present and confident, it replaces percentile guesses.
     */
    print?: BandProfile | null;
    printConfidence?: number;
}
/** A noise print is only trusted as a floor measurement above this confidence. */
export declare const TRUSTED_PRINT_CONFIDENCE = 0.35;
/**
 * Build the noise model from measured band statistics.
 * Every field stays null when its inputs are unavailable.
 */
export declare function buildNoiseModel(input: NoiseModelInput): NoiseModel;
/**
 * Highest frequency still carrying performance. Walks down from the top and
 * stops at the first band holding signal, so a hiss shelf above the real
 * bandwidth is not mistaken for content.
 */
export declare function estimateBandwidthHz(bands: BandVerdict[], nyquistHz: number | null): number | null;
/**
 * Loudest stationary-noise band on one side of a frequency, relative to the
 * music core. Returns null when no band there reads as noise.
 */
export declare function stationaryNoiseRelativeDb(bands: BandVerdict[], musicReferenceDb: number | null, frequencyHz: number, side: "above" | "below"): number | null;
/**
 * Score how audible a stationary noise region is, 0–1.
 * -55 dB below the music core is inaudible; -20 dB is intrusive.
 */
export declare function audibilityScore(relativeDb: number | null): number | null;
/**
 * Confidence that a measured narrow-band excess is mains hum rather than music.
 * A musical note in that band comes and goes; hum is a fixed line sitting well
 * above the spectrum either side of it.
 */
export declare function humConfidence(excessDb: number | null): number;