Adaptive Multi-Rate ACELP (.amr)
.amr file signature | audio/amr
Adaptive Multi-Rate (AMR) is a speech audio format and codec standardized and maintained by the 3rd Generation Partnership Project (3GPP). It is used for voice recording, mobile telephony, Voice over IP, and other narrowband speech applications. AMR is generally considered safe to handle, and it has long been associated with cellular networks, where it was designed to improve speech compression and adaptation across varying network conditions.
Magic Bytes
Offset 0
23 21 41 4D 52
Sources: Apache Tika, Wikipedia, Gary Kessler, Neil Harvey FileSignatures
All Known Signatures
2 signature variants are documented for .amr files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 23 21 41 4D 52 | 0 | Apache Tika, Wikipedia, Gary Kessler, Neil Harvey FileSignatures |
| 23 21 41 4D 52 0A | 0 | Apache Tika |
Extension
.amr
MIME Type
audio/amr
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .amr files in Python
def is_amr(file_path: str) -> bool:
"""Check if file is a valid AMR by magic bytes."""
signature = bytes([0x23, 0x21, 0x41, 0x4D, 0x52])
with open(file_path, "rb") as f:
return f.read(5) == signatureHow to validate .amr files in Node.js
function isAMR(buffer: Buffer): boolean {
const signature = Buffer.from([0x23, 0x21, 0x41, 0x4D, 0x52]);
return buffer.subarray(0, 5).equals(signature);
}How to validate .amr files in Go
func IsAMR(data []byte) bool {
signature := []byte{0x23, 0x21, 0x41, 0x4D, 0x52}
if len(data) < 5 {
return false
}
return bytes.Equal(data[:5], signature)
}API Endpoint
/api/v1/amr
curl https://filesignature.org/api/v1/amr
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .amr file?
A .amr file is a Adaptive Multi-Rate ACELP file. Adaptive Multi-Rate (AMR) is a speech audio format and codec standardized and maintained by the 3rd Generation Partnership Project (3GPP). It is used for voice recording, mobile telephony, Voice over IP, and other narrowband speech applications. AMR is generally considered safe to handle, and it has long been associated with cellular networks, where it was designed to improve speech compression and adaptation across varying network conditions.
What are the magic bytes for .amr files?
The magic bytes for Adaptive Multi-Rate ACELP files are 23 21 41 4D 52 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .amr file?
To validate a .amr file, read the first bytes of the file and compare them against the known magic bytes (23 21 41 4D 52) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .amr files?
The primary MIME type for .amr files is audio/amr.
Is it safe to open .amr files?
Adaptive Multi-Rate ACELP (.amr) 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.