import { Size } from "../../models/rendering";
import { SpectrogramOptions } from "../../components/spectrogram/spectrogramOptions";
import { AudioInformation } from "./audioInformation";
export declare class AudioHelper {
    private readonly spectrogramWorker;
    private readonly state;
    private readonly sampleBuffer;
    private cachedResponse;
    private cachedAudioInformation;
    private offscreenCanvas;
    private generationData;
    private segmentSize;
    private generation;
    constructor();
    get canvasTransferred(): boolean;
    connect(src: string, canvas: HTMLCanvasElement, options: SpectrogramOptions): Promise<Readonly<AudioInformation>>;
    changeSource(src: string, options: SpectrogramOptions): Promise<AudioInformation>;
    regenerateSpectrogram(options: SpectrogramOptions): Promise<void>;
    resizeCanvas(size: Size): void;
    /**
     * Gracefully stop any in-flight processing and free underlying resources.
     * - Aborts the current render generation and waits for the worker to become idle
     * - Terminates the spectrogram worker
     */
    destroy(): Promise<void>;
    private abort;
    /**
     * Internal render function. Does not check if we need to abort.
     * @param options the spectrogram options
     * @param generation the generation number
     * @param src  if provided fetches the audio at the supplied source, otherwise clones a buffer of the last response
     */
    private render;
    private createAudioInformation;
    private fetchAudio;
    private cachedBuffer;
    /**
     * Creates and prepares the audio context, but does NOT start rendering.
     * Returns a callback to start rendering, or undefined if setup failed.
     * This separation allows the caller to ensure the worker is ready before
     * the OfflineAudioContext begins pumping data through the processor.
     */
    private createAudioContext;
    private setupWorker;
    private setupProcessor;
    private clearCanvas;
    private regenerateWorker;
}