/**
 * Scheduler -- clock abstraction decoupling animation from requestAnimationFrame.
 *
 * Four implementations:
 *   - raf: browser real-time (default)
 *   - noop: SSR-safe
 *   - fixedStep: deterministic timestamps at target fps (video rendering)
 *   - audioSync: ticks in lockstep with an AVBridge sample counter
 *
 * @module
 */
import type { AVBridge } from './av-bridge.js';
interface SchedulerShape {
    readonly _tag: 'FrameScheduler';
    schedule(callback: (now: number) => void): number;
    cancel(id: number): void;
}
interface FixedStepShape extends SchedulerShape {
    step(): void;
    readonly frame: number;
}
/** Default: requestAnimationFrame. Used by Timeline/animate in browser. */
declare function _raf(): SchedulerShape;
/** SSR-safe: noop scheduler for server environments. */
declare function _noop(): SchedulerShape;
declare function _fixedStep(fps: number): FixedStepShape;
interface AudioSyncShape extends SchedulerShape {
    poll(): void;
    readonly frame: number;
    readonly bridge: AVBridge.Shape;
}
declare function _audioSync(bridge: AVBridge.Shape): AudioSyncShape;
/**
 * Scheduler — clock abstraction that decouples animation driver from real time.
 * Pick the impl that matches the runtime: `raf` in browser, `noop` on the
 * server, `fixedStep` for deterministic video render, `audioSync` to drive UI
 * in lockstep with an {@link AVBridge}.
 */
export declare const Scheduler: {
    /** `requestAnimationFrame`-backed scheduler for browser real-time work. */
    raf: typeof _raf;
    /** No-op scheduler for SSR / environments without rAF. */
    noop: typeof _noop;
    /** Fixed-step scheduler at the given fps — deterministic timestamps for offline rendering. */
    fixedStep: typeof _fixedStep;
    /** Scheduler that polls an {@link AVBridge} and fires callbacks when the sample frame advances. */
    audioSync: typeof _audioSync;
};
export declare namespace Scheduler {
    /** Common structural shape every scheduler variant satisfies. */
    type Shape = SchedulerShape;
    /** Fixed-step scheduler with manual `step()` advancement. */
    type FixedStep = FixedStepShape;
    /** Audio-synchronized scheduler bound to an {@link AVBridge}. */
    type AudioSync = AudioSyncShape;
}
export {};
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