/**
 * iOS Safari exposes a non-standard `"interrupted"` state in addition to the
 * spec'd `AudioContextState`s when the audio session is taken away (e.g. the
 * device is locked or another app starts playing audio).
 * @see https://developer.mozilla.org/en-US/docs/Web/API/BaseAudioContext/state#resuming_interrupted_play_states_in_ios_safari
 */
export type InterruptibleAudioContextState = AudioContextState | "interrupted";
/**
 * @internal
 * Pure policy deciding whether `AudioContext.resume()` should be attempted right now.
 *
 * The context needs resuming when it is `"suspended"` or (on iOS) `"interrupted"`.
 * But resuming is only allowed while the document is **visible**: on iOS Safari,
 * calling `resume()` while the page is backgrounded or the device is locked fails
 * with `InvalidStateError: Failed to start the audio device`, because the audio
 * hardware cannot be started in the background. In that case the resume must be
 * deferred until the page becomes visible again.
 *
 * @param state The current (possibly iOS-interrupted) audio context state.
 * @param visibility The current `document.visibilityState`.
 * @returns `true` if `resume()` should be called now, `false` if it should be deferred.
 */
export declare function shouldResumeAudioContext(state: InterruptibleAudioContextState, visibility: DocumentVisibilityState): boolean;
/**
 * @internal
 * Keep the shared AudioContext alive across suspends/interruptions (tab switch, device lock, audio
 * session interruption). On returning to the foreground we simply resume() the EXISTING context —
 * the same approach three.js uses, which recovers cleanly because AudioSource plays clips through a
 * MediaElementAudioSourceNode (an <audio> element), whose media session iOS keeps alive across a
 * lock. We deliberately do NOT close/recreate the context: on-device testing showed that makes iOS
 * worse (a recreated context's output stays dead) and it is unnecessary.
 */
export declare function ensureAudioContextIsResumed(): void;
/**
 * Represents an audio clip that can be loaded and played independently.
 * The AudioClip class encapsulates the URL of the audio resource and provides
 * methods for playback control (play, pause, stop) and querying duration.
 */
export declare class AudioClip {
    readonly url: string;
    /**
     * Creates a new AudioClip instance with the specified URL.
     * @param url The URL of the audio resource to load. This can be a path to an audio file or a MediaStream URL.
     */
    constructor(url: string);
    /** Whether the clip is currently playing.
     * @returns `true` if the clip is actively playing audio.
     */
    get isPlaying(): boolean;
    /**
     * The total duration of the audio clip in seconds.
     * Loads the audio metadata if not already available.
     * @returns A promise that resolves with the duration in seconds.
     */
    getDuration(): Promise<number>;
    /**
     * Plays the audio clip from the current position.
     * @returns A promise that resolves when playback finishes, or rejects on error.
     * If the clip is looping, the promise will never resolve on its own – call {@link stop} or {@link pause} to end playback.
     */
    play(): Promise<void>;
    /**
     * Pauses playback at the current position.
     * Call {@link play} to resume.
     */
    pause(): void;
    /**
     * Stops playback and resets the position to the beginning.
     */
    stop(): void;
    /** Whether the clip should loop when reaching the end. */
    get loop(): boolean;
    set loop(value: boolean);
    /** Playback volume from 0 (silent) to 1 (full). */
    get volume(): number;
    set volume(value: number);
    /** Current playback position in seconds. */
    get currentTime(): number;
    set currentTime(value: number);
    /** Normalized playback progress from 0 to 1.
     * @returns The current playback position as a value between 0 and 1, or 0 if the duration is unknown.
     */
    get progress(): number;
    /**
     * Seeks to a normalized position (0–1) in the clip.
     * @param position A value between 0 (start) and 1 (end).
     */
    seek(position: number): void;
    /** The underlying HTMLAudioElement, or `undefined` if not yet created.
     * Use this to connect the element to the Web Audio API via `createMediaElementSource()`.
     * @returns The HTMLAudioElement if the clip has been loaded or played, otherwise `undefined`.
     */
    get audioElement(): HTMLAudioElement | undefined;
    private _audioElement?;
    private _duration?;
    private _loadPromise?;
    private _loop;
    private _volume;
    /** Lazily creates and loads the shared HTMLAudioElement. */
    private ensureAudioElement;
}