ISO Base Media file
video/mp4
Magic Bytes
Offset: 4
66 74 79 70 6D 70 34 32
The MPEG-4 Part 14 (MP4) format is a digital multimedia container standard defined by ISO/IEC as part of the broader MPEG-4 specification. It is universally utilized for storing digital video and audio streams, as well as subtitles and still images, making it the ubiquitous standard for internet streaming. Based directly on the Apple QuickTime File Format, MP4 is generally safe, though malformed containers can potentially trigger vulnerabilities in outdated media players.
Validation Code
How to validate .mp4 files in Python
Python
def is_mp4(file_path: str) -> bool:
"""
Check if file is a valid MP4 by magic bytes.
Signature offset: 4 bytes
"""
signature = bytes([0x66, 0x74, 0x79, 0x70, 0x6D, 0x70, 0x34, 0x32])
with open(file_path, "rb") as f:
f.seek(4)
return f.read(8) == signatureHow to validate .mp4 files in Node.js
Node.js
function isMP4(buffer: Buffer): boolean {
// Signature offset: 4 bytes
const signature = Buffer.from([0x66, 0x74, 0x79, 0x70, 0x6D, 0x70, 0x34, 0x32]);
if (buffer.length < 12) return false;
return buffer.subarray(4, 12).equals(signature);
}
Go
func IsMP4(data []byte) bool {
// Signature offset: 4 bytes
signature := []byte{0x66, 0x74, 0x79, 0x70, 0x6D, 0x70, 0x34, 0x32}
if len(data) < 12 {
return false
}
return bytes.Equal(data[4:12], signature)
}API Endpoint
GET
/api/v1/mp4
curl https://filesignature.org/api/v1/mp4