export interface RationalTime {
    readonly numerator: bigint;
    readonly denominator: bigint;
}
export interface RationalTimeInput {
    numerator: bigint | number | string;
    denominator: bigint | number | string;
}
export declare function rationalTime(input: RationalTimeInput): RationalTime;
export declare function rationalTimeKey(input: RationalTimeInput): string;
export declare function rationalTimeToSeconds(input: RationalTimeInput): number;
export declare function parsePositiveNumber(source: string, field: string, allowZero?: boolean): number;
export declare function parseInteger(source: string, field: string, options?: {
    positive?: boolean;
    nonNegative?: boolean;
}): number;
/**
 * Converts a V1 time literal to an integer frame using exact rational
 * arithmetic. Values between frame boundaries are rounded to the nearest frame;
 * ties round away from zero. Timeline calculations after this conversion only
 * use integers.
 */
export declare function parseTimeToFrames(source: string, fpsSource: string, field?: string): number;
export declare function framesToSeconds(frames: number, fps: number): number;
export declare function framesToFfmpegSeconds(frames: number, fpsSource: string): string;
export declare function framesToSamples(frames: number, sampleRate: number, fpsSource: string): number;
/**
 * Returns the smallest whole-frame duration that fully contains an audio
 * waveform. This deliberately rounds up so the subtitle never disappears
 * before its final audio sample.
 */
export declare function samplesToCoveringFrames(samples: number, sampleRate: number, fpsSource: string): number;
export interface TimelinePhaseSample {
    readonly phase: "before" | "active" | "after";
    readonly localTime: RationalTime;
}
/** Exact frame-start clock used by every DOM timeline caller. */
export declare class SampleClock {
    readonly fps: RationalTime;
    constructor(source: string | number | RationalTimeInput);
    frameStart(frame: number): RationalTime;
    frameAt(input: RationalTimeInput): number;
    toMilliseconds(input: RationalTimeInput): number;
    phase(input: RationalTimeInput, start: RationalTimeInput, duration: RationalTimeInput, fill: "none" | "forwards" | "backwards" | "both"): TimelinePhaseSample | undefined;
}
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