MPEG-4 Advanced Audio Coding (.aac)
.aac file signature | audio/x-aac
MPEG-4 Advanced Audio Coding (AAC) Low Complexity (LC) audio file
Magic Bytes
Offset 0
49 44 33
Sources: Apache Tika
All Known Signatures
3 signature variants are documented for .aac files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 49 44 33 | 0 | Apache Tika |
| FF F1 | 0 | Gary Kessler |
| FF F9 | 0 | Gary Kessler |
Extension
.aac
MIME Type
audio/x-aac
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .aac files in Python
def is_aac(file_path: str) -> bool:
"""Check if file is a valid AAC by magic bytes."""
signature = bytes([0x49, 0x44, 0x33])
with open(file_path, "rb") as f:
return f.read(3) == signatureHow to validate .aac files in Node.js
function isAAC(buffer: Buffer): boolean {
const signature = Buffer.from([0x49, 0x44, 0x33]);
return buffer.subarray(0, 3).equals(signature);
}How to validate .aac files in Go
func IsAAC(data []byte) bool {
signature := []byte{0x49, 0x44, 0x33}
if len(data) < 3 {
return false
}
return bytes.Equal(data[:3], signature)
}API Endpoint
/api/v1/aac
curl https://filesignature.org/api/v1/aac
See the full API documentation for all endpoints and parameters.
Frequently Asked Questions
What is a .aac file?
A .aac file is a MPEG-4 Advanced Audio Coding file. MPEG-4 Advanced Audio Coding (AAC) Low Complexity (LC) audio file
What are the magic bytes for .aac files?
The magic bytes for MPEG-4 Advanced Audio Coding files are 49 44 33 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .aac file?
To validate a .aac file, read the first bytes of the file and compare them against the known magic bytes (49 44 33) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .aac files?
The primary MIME type for .aac files is audio/x-aac.
Is it safe to open .aac files?
MPEG-4 Advanced Audio Coding (.aac) 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.