/**
 * Cheap, dependency-free duration probes for uploaded media that is already
 * in memory (≤ 25 MB). Supports ISO-BMFF (MP4/MOV/M4V/M4A, via mvhd), WAV
 * (RIFF byte rate) and MP3 (frame scan). Returns undefined for anything else
 * or for malformed input; never throws.
 */
export declare function mediaDurationSeconds(buffer: Buffer, contentType?: string): number | undefined;