import type { InterpolationStrategyParams, RateTransposerInterpolationStrategy, SampleBufferType, StretchParameters } from '@soundtouchjs/core';
export type { StretchParameters } from '@soundtouchjs/core';
/**
 * Snapshot of processor performance metrics received from the render thread.
 *
 * @remarks
 * Emitted every 100 render blocks via the `metrics` CustomEvent.
 * Access the latest snapshot via `FormantCorrectionNode.metrics`.
 */
export interface ProcessorMetrics {
    /** Frames available in the output buffer at the last render block. */
    framesBuffered: number;
    /** Cumulative render blocks where the output buffer had fewer frames than requested. */
    underrunCount: number;
    /** Total render blocks processed since the processor was created. */
    blockCount: number;
    /** `performance.now()` timestamp recorded on the main thread when metrics arrived. */
    timestamp: DOMHighResTimeStamp;
}
/**
 * Construction options for `FormantCorrectionNode`.
 */
export interface FormantCorrectionNodeOptions {
    /** Internal sample buffer strategy. */
    sampleBufferType?: SampleBufferType;
    /** Rate-transposer interpolation strategy. */
    interpolationStrategy?: RateTransposerInterpolationStrategy;
}
/**
 * Construction options for the `FormantCorrectionNode` constructor.
 */
export interface FormantCorrectionNodeConstructorOptions extends FormantCorrectionNodeOptions {
    /**
     * AudioContext or OfflineAudioContext for node construction.
     */
    context: BaseAudioContext;
    /**
     * Number of output channels. Defaults to `2` (stereo).
     *
     * @remarks
     * Set to `1` when connecting to a mono destination. The processor always
     * processes interleaved stereo internally. Mono input is always supported —
     * the processor duplicates a single input channel to both stereo sides.
     */
    outputChannelCount?: 1 | 2;
}
/**
 * Main-thread AudioWorkletNode that applies SoundTouch pitch-shifting with
 * LPC-based formant correction.
 *
 * @remarks
 * Wraps `FormantCorrectionProcessor` and provides the same AudioParam accessors
 * as `SoundTouchNode`, plus a `formantStrength` param that controls how strongly
 * the original formant envelope is preserved after pitch shifting.
 *
 * - `formantStrength = 0` — identical output to `SoundTouchNode` (no correction)
 * - `formantStrength = 1` — original formants fully preserved at the new pitch
 *
 * @example
 * ```ts
 * import { FormantCorrectionNode } from '@soundtouchjs/formant-correction-worklet';
 *
 * await FormantCorrectionNode.register(audioCtx, processorUrl);
 * const node = new FormantCorrectionNode({ context: audioCtx });
 * node.pitchSemitones.value = 7;   // up a fifth
 * node.formantStrength.value = 1;  // keep original timbre
 * ```
 */
export declare class FormantCorrectionNode extends AudioWorkletNode {
    /**
     * The registered processor name for this node type.
     */
    static readonly processorName = "formant-correction-processor";
    /**
     * Registers the formant correction processor module with the given AudioContext.
     *
     * @param context - The AudioContext or OfflineAudioContext.
     * @param processorUrl - URL or path to the processor bundle.
     */
    static register(context: BaseAudioContext, processorUrl: string | URL): Promise<void>;
    /**
     * Registers an interpolation strategy installer module in AudioWorkletGlobalScope.
     *
     * @remarks
     * The module should call core registration APIs during evaluation.
     */
    static registerStrategyModule(context: BaseAudioContext, strategyModuleUrl: string | URL): Promise<void>;
    private _lastMetrics;
    /**
     * Creates a `FormantCorrectionNode` instance.
     * @param options - Node and processor configuration.
     */
    constructor({ context, sampleBufferType, interpolationStrategy, outputChannelCount, }: FormantCorrectionNodeConstructorOptions);
    /**
     * Returns the most recent processor metrics, or `null` before the first report.
     *
     * @remarks
     * Updated every 100 render blocks. Also dispatched as a `metrics` CustomEvent.
     */
    get metrics(): ProcessorMetrics | null;
    /**
     * Pitch multiplier AudioParam (1.0 = original pitch).
     */
    get pitch(): AudioParam;
    /**
     * Semitone pitch shift AudioParam (integer steps for musical key changes).
     */
    get pitchSemitones(): AudioParam;
    /**
     * Playback rate AudioParam. Set to match the source node's `playbackRate`
     * for accurate pitch compensation.
     */
    get playbackRate(): AudioParam;
    /**
     * Formant correction strength AudioParam (0.0–1.0, k-rate).
     *
     * @remarks
     * - `0.0` — no correction; output is identical to `SoundTouchNode`.
     * - `1.0` — full correction; original vocal formants are preserved at the new pitch.
     * - Intermediate values linearly blend the corrected and uncorrected signals.
     */
    get formantStrength(): AudioParam;
    /**
     * Switches interpolation strategy at runtime in the render-thread processor.
     * @param strategy The new interpolation strategy to use.
     */
    setInterpolationStrategy(strategy: RateTransposerInterpolationStrategy): void;
    /**
     * Applies a partial params update to the active interpolation strategy.
     * @param params Partial set of parameters to update.
     */
    setInterpolationStrategyParams(params: Partial<InterpolationStrategyParams>): void;
    /**
     * Applies WSOLA timing parameter updates to the render-thread processor.
     * @param params WSOLA timing parameters.
     */
    setStretchParameters(params: StretchParameters): void;
}
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