/**
 * Converts seconds elapsed since `windowStart` to an ISO 8601 basic timestamp.
 * Format: `YYYYMMDDTHHMMSSZ` (e.g. `20260130T191055Z`).
 *
 * Pass midnight of a day (`new Date(y, m, d)`) to retain the previous
 * seconds-in-day behaviour. Pass any other Date to support cross-midnight windows.
 */
export declare function secondsToTimestamp(secondsFromWindowStart: number, windowStart: Date): string;
export declare function getNowInDaySeconds(nowMs?: number): number;
export declare function formatHmsFromSeconds(secondsInDay: number): string;
export declare function formatHmsfFromSeconds(secondsInDay: number, fps: number): string;
export declare function formatDurationHms(seconds: number): string;
export declare function formatDurationHmsf(seconds: number, fps: number): string;
