import type { Config } from "../config.js";
/**
 * Downloads audio from a video URL in the best available quality.
 *
 * @param url - The URL of the video to extract audio from
 * @param config - Configuration object for download settings
 * @returns Promise resolving to a success message with the downloaded file path
 * @throws {Error} When URL is invalid or download fails
 *
 * @example
 * ```typescript
 * // Download audio with default settings
 * const result = await downloadAudio('https://youtube.com/watch?v=...');
 * console.log(result);
 *
 * // Download audio with custom config
 * const customResult = await downloadAudio('https://youtube.com/watch?v=...', {
 *   file: {
 *     downloadsDir: '/custom/path',
 *     // ... other config options
 *   }
 * });
 * console.log(customResult);
 * ```
 */
export declare function downloadAudio(url: string, config: Config): Promise<string>;