MP4A
audio/mp4
Magic Bytes
Offset: 4
66 74 79 70 4D 34 41 20
The MP4A file format is an audio-only MPEG-4 container developed by the Moving Picture Experts Group (MPEG) and frequently adopted by Apple ecosystems. It is widely used for distributing digital music, audiobooks, and podcasts, typically serving as a wrapper for Advanced Audio Coding (AAC) or Apple Lossless data. Although structurally similar to standard MP4 video files, this specific variant isolates audio streams and is considered safe for general use across all major operating systems.
Validation Code
How to validate .mp4a files in Python
Python
def is_mp4a(file_path: str) -> bool:
"""
Check if file is a valid MP4A by magic bytes.
Signature offset: 4 bytes
"""
signature = bytes([0x66, 0x74, 0x79, 0x70, 0x4D, 0x34, 0x41, 0x20])
with open(file_path, "rb") as f:
f.seek(4)
return f.read(8) == signatureHow to validate .mp4a files in Node.js
Node.js
function isMP4A(buffer: Buffer): boolean {
// Signature offset: 4 bytes
const signature = Buffer.from([0x66, 0x74, 0x79, 0x70, 0x4D, 0x34, 0x41, 0x20]);
if (buffer.length < 12) return false;
return buffer.subarray(4, 12).equals(signature);
}
Go
func IsMP4A(data []byte) bool {
// Signature offset: 4 bytes
signature := []byte{0x66, 0x74, 0x79, 0x70, 0x4D, 0x34, 0x41, 0x20}
if len(data) < 12 {
return false
}
return bytes.Equal(data[4:12], signature)
}API Endpoint
GET
/api/v1/mp4a
curl https://filesignature.org/api/v1/mp4a