Apple Lossless Audio Codec file (.m4a)
.m4a file signature | audio/mp4
M4A is an audio file format developed by Apple as part of the MPEG-4 media standard and commonly used for Apple Lossless Audio Codec content. It is used for music distribution, audio playback, podcasts, and storage in applications such as iTunes, Apple Music, and other media players. The format is generally safe, though files from untrusted sources may contain malformed metadata or embedded content that can affect vulnerable software.
Magic Bytes
Offset 4
66 74 79 70 4D 34 41 20
Sources: Apache Tika, Gary Kessler
All Known Signatures
6 signature variants are documented for .m4a files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 66 74 79 70 4D 34 41 20 | 4 | Apache Tika, Gary Kessler |
| 66 74 79 70 4D 34 42 20 | 4 | Apache Tika |
| 66 74 79 70 46 34 41 20 | 4 | Apache Tika |
| 66 74 79 70 46 34 42 20 | 4 | Apache Tika |
| 66 74 79 70 33 67 70 | 4 | Gary Kessler |
| 4D 34 41 20 | 0 | Neil Harvey FileSignatures |
Extension
.m4a
MIME Type
audio/mp4
Byte Offset
4
Risk Level
Safe
Validation Code
How to validate .m4a files in Python
def is_m4a(file_path: str) -> bool:
"""Check if file is a valid M4A by magic bytes at offset 4."""
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 .m4a files in Node.js
function isM4A(buffer: Buffer): boolean {
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);
}How to validate .m4a files in Go
func IsM4A(data []byte) bool {
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
/api/v1/m4a
curl https://filesignature.org/api/v1/m4a
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .m4a file?
A .m4a file is a Apple Lossless Audio Codec file file. M4A is an audio file format developed by Apple as part of the MPEG-4 media standard and commonly used for Apple Lossless Audio Codec content. It is used for music distribution, audio playback, podcasts, and storage in applications such as iTunes, Apple Music, and other media players. The format is generally safe, though files from untrusted sources may contain malformed metadata or embedded content that can affect vulnerable software.
What are the magic bytes for .m4a files?
The magic bytes for Apple Lossless Audio Codec file files are 66 74 79 70 4D 34 41 20 at byte offset 4. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .m4a file?
To validate a .m4a file, read the first bytes of the file and compare them against the known magic bytes (66 74 79 70 4D 34 41 20) at offset 4. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .m4a files?
The primary MIME type for .m4a files is audio/mp4.
Is it safe to open .m4a files?
Apple Lossless Audio Codec file (.m4a) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.