/**
 * @param {Blob | string} blob
 * @returns {Promise<number>} Blob duration in seconds.
 */
export default function getBlobDuration(blob: Blob | string): Promise<number>;
/**
 * Convert base64 string to ArrayBuffer.
 * @param base64 The base64 string to convert.
 * @returns The converted ArrayBuffer.
 * @remarks This function is exported for test coverage purposes.
 */
export declare function base64ToArrayBuffer(base64: string): ArrayBuffer;