import type { BasePlaylistItem } from '@nomercy-entertainment/nomercy-player-core';
import type { IThumbnailSource, ThumbnailFrame } from './IThumbnailSource.js';
/**
 * Default thumbnail source. Fetches a WebVTT sprite manifest from
 * `item.previewSpriteUrl`, parses the cue list, preloads the sprite image,
 * and exposes synchronous `lookup(time)` for progress-bar hover rendering.
 *
 * The VTT cue body format expected is:
 *   `sprite.webp#xywh=x,y,w,h`
 *
 * This is the format produced by NoMercy's media-server sprite generator
 * and is compatible with industry-standard tooling (ffmpeg tileify filters,
 * JW Player sprite format).
 */
export declare class VttSpriteThumbnailSource implements IThumbnailSource {
    private _cache;
    load(item: BasePlaylistItem): Promise<boolean>;
    lookup(timeSeconds: number): ThumbnailFrame | null;
    unload(): void;
    private _resolveSpriteUrl;
}