/**
 * Metrics collected from a video element's rendered frames.
 */
export interface VideoElementFrameMetrics {
    /**
     * Current frames per second.
     */
    fps: number;
    /**
     * Timestamp of the measurement in milliseconds since epoch.
     */
    timestampMs: number;
}
/**
 * Observer for frame-level events on a video element.
 */
export interface VideoElementFrameObserver {
    /**
     * Called when the first video frame is rendered.
     * @param metadata The VideoFrameCallbackMetadata, if available (only on browsers supporting requestVideoFrameCallback)
     */
    firstVideoElementFrameDidRender?(metadata?: VideoFrameCallbackMetadata): void;
    /**
     * Called periodically with render metrics (e.g. FPS).
     * Only fires on browsers that support requestVideoFrameCallback.
     * @param metrics The collected metrics
     */
    videoElementFrameMetricsDidReceive?(metrics: VideoElementFrameMetrics): void;
}
/**
 * Monitors a video element for first-frame rendering and ongoing FPS metrics.
 *
 * Internally uses requestVideoFrameCallback when available (Chrome/Edge) and
 * falls back to the 'resize' event for first-frame detection on other browsers.
 * FPS tracking is only available when requestVideoFrameCallback is supported.
 */
export default class VideoElementFrameMonitor {
    private static readonly METRICS_INTERVAL_MS;
    private element;
    private observer;
    private firstFrameRendered;
    private videoFrameCallbackId;
    private metricsCallbackId;
    private frameCount;
    private metricsWindowStartMs;
    private resizeListener;
    private get supportsVideoFrameCallback();
    /**
     * Start monitoring the given element with the given observer.
     * Any previous monitoring is stopped first.
     */
    start(element: HTMLVideoElement, observer: VideoElementFrameObserver): void;
    /**
     * Stop monitoring and release all resources.
     */
    stop(): void;
    private startFirstFrameDetection;
    private onFirstFrame;
    private startMetricsTracking;
    private scheduleMetricsCallback;
    private stopMetricsTracking;
}