import type { PlaybackState } from "../types.js";
/**
 * Determines if MP4 fallback should be used based on HLS state and availability.
 * Returns true if:
 * 1. HLS is in error state (fatal error occurred)
 * 2. fallbackSrc is available
 */
export declare function shouldUseMp4Fallback(hlsState: PlaybackState, fallbackSrc?: string): boolean;