Aud
1s Silence M4A
1s Silence M4A is a MPEG-4 Audio sample generated for file format testing. It can be used to test downloads, parsers, previews, and file type detection.
silence-1s.m4aType Sample
1.2 KB DownloadAudio
M4A MPEG-4 Audio
MPEG-4 Audio is a audio format commonly identified by .m4a. Use the listed signatures, MIME types, and structure notes to validate files beyond the extension.
Extensions .m4a
MIME audio/mp4
Magic numbers
Analyze your fileoffset 4 MPEG-4 Audio signature at byte offset 4
66 74 79 70 ftypStructure
- ftyp box
- moov box
- mdat box
Caveats
- Do not trust the extension alone. Check the MIME type, the first bytes such as 66 74 79 70, and format-specific structure when possible.
- Container formats and damaged files can share the same opening bytes, so deeper validation may be required for production upload, preview, or conversion flows.
Detection example
SIGNATURE = bytes.fromhex("66747970")
OFFSET = 4
def is_m4a(path: str) -> bool:
with open(path, "rb") as f:
f.seek(OFFSET)
head = f.read(len(SIGNATURE))
return head == SIGNATUREconst SIGNATURE = [0x66, 0x74, 0x79, 0x70];
const OFFSET = 4;
// bytes: a Uint8Array / Buffer holding the start of the file
export function isM4a(bytes) {
return SIGNATURE.every((byte, i) => bytes[OFFSET + i] === byte);
}package fileid
import "bytes"
var ism4aSignature = []byte{0x66, 0x74, 0x79, 0x70}
const ism4aOffset = 4
func IsM4a(b []byte) bool {
end := ism4aOffset + len(ism4aSignature)
if len(b) < end {
return false
}
return bytes.Equal(b[ism4aOffset:end], ism4aSignature)
}const SIGNATURE: &[u8] = &[0x66, 0x74, 0x79, 0x70];
const OFFSET: usize = 4;
fn is_m4a(bytes: &[u8]) -> bool {
bytes.get(OFFSET..OFFSET + SIGNATURE.len()) == Some(SIGNATURE)
}<?php
$signature = "\x66\x74\x79\x70";
$offset = 4;
function is_m4a(string $bytes): bool {
global $signature, $offset;
return substr($bytes, $offset, strlen($signature)) === $signature;
}Practical usage
Use cases
MPEG-4 Audio is used for playback, waveform processing, upload checks, duration handling, and bitrate validation. Short clips, silence, and ambient audio help expose player and conversion edge cases.
Common detection mistakes
- The .m4a extension alone does not prove the file contents. Upload and conversion flows should combine extension, MIME type, leading bytes, and format-specific structure checks.
- MPEG-4 Audio can start with signatures such as 66 74 79 70, but related containers and damaged files may require additional validation.
Security notes
Media files can still stress decoders through corrupt metadata, extreme dimensions, long durations, or unusual chunks. Read size, dimensions, and duration before processing.
Using samples
11 samples help test duration handling, playback startup, metadata reads, and download behavior.
Sample files
11 / 11 filesAud
Lake Waves M4A 0.25s
Lake Waves M4A 0.25s is a MPEG-4 Audio sample based on Wikimedia Commons, 0.25s. It can be used to test downloads, parsers, previews, and file type detection.
01-lake-waves.m4aDuration 0.25s
3.9 KB SHA-256
3acf7a99014ee51084844dfa48809d4fec35e64e6a3dd60ed570a6a2a39f7375Aud
Lake Waves M4A 0.5s
Lake Waves M4A 0.5s is a MPEG-4 Audio sample based on Wikimedia Commons, 0.5s. It can be used to test downloads, parsers, previews, and file type detection.
02-lake-waves.m4aDuration 0.5s
6.6 KB SHA-256
e42cf698af2b9a5ed2b1e9748a6d701e5670c9aed139214f351aac04b425c731Aud
Lake Waves M4A 1s
Lake Waves M4A 1s is a MPEG-4 Audio sample based on Wikimedia Commons, 1s. It can be used to test downloads, parsers, previews, and file type detection.
03-lake-waves.m4aDuration 1s
13 KB SHA-256
d276f4457c6a8279a76b3d6441fe376199b28f3e58743032cc22f32a4eeab73fAud
Lake Waves M4A 1.5s
Lake Waves M4A 1.5s is a MPEG-4 Audio sample based on Wikimedia Commons, 1.5s. It can be used to test downloads, parsers, previews, and file type detection.
04-lake-waves.m4aDuration 1.5s
19 KB SHA-256
9bb5abfe5902192df5eea9ff612be786a6a66e6f9a81f6e9b8752985367c9d7eAud
Lake Waves M4A 2s
Lake Waves M4A 2s is a MPEG-4 Audio sample based on Wikimedia Commons, 2s. It can be used to test downloads, parsers, previews, and file type detection.
05-lake-waves.m4aDuration 2s
25 KB SHA-256
333f53255cde3ea10ec6a204df25ef0120c2d2e1a18deab7d69cbbf1088b1015Aud
Lake Waves M4A 3s
Lake Waves M4A 3s is a MPEG-4 Audio sample based on Wikimedia Commons, 3s. It can be used to test downloads, parsers, previews, and file type detection.
06-lake-waves.m4aDuration 3s
37 KB SHA-256
a0df51be67619ee1285dc2ff7c3eddf1fd96d7c61d77d7af5a674035b44c8fd4Aud
Lake Waves M4A 4s
Lake Waves M4A 4s is a MPEG-4 Audio sample based on Wikimedia Commons, 4s. It can be used to test downloads, parsers, previews, and file type detection.
07-lake-waves.m4aDuration 4s
49 KB SHA-256
f273420fb35c21dbf949b983c3c290b7b236fe68463d3603a88a0f1581d9ea76Aud
Lake Waves M4A 6s
Lake Waves M4A 6s is a MPEG-4 Audio sample based on Wikimedia Commons, 6s. It can be used to test downloads, parsers, previews, and file type detection.
08-lake-waves.m4aDuration 6s
73 KB SHA-256
ec4cfe7733673a288bd3ce55009ff2673d39978a459cd7edef1acc8799691f5eAud
Lake Waves M4A 8s
Lake Waves M4A 8s is a MPEG-4 Audio sample based on Wikimedia Commons, 8s. It can be used to test downloads, parsers, previews, and file type detection.
09-lake-waves.m4aDuration 8s
96 KB SHA-256
f0c43b06e3c2f562cea9301844bcb35b77f638e1e864bb4cc267714d6a4de38fAud
NASA TV Audio M4A
NASA TV Audio M4A is a MPEG-4 Audio sample based on NASA Image and Video Library, 2s. It can be used to test downloads, parsers, previews, and file type detection.
nasa-tv-audio.m4aDuration 2s
25 KB SHA-256
8cf1d4f56a731eb009dcc14b10952c4b39e4d35d20bb6c6ec99b5f2016b3b21aFrequently asked questions
What is the magic number (file signature) of MPEG-4 Audio?
MPEG-4 Audio files begin with the byte signature 66 74 79 70 ("ftyp"). Detect the format by reading these leading bytes rather than trusting the file extension alone.
What is the MIME type of MPEG-4 Audio?
The MIME type for MPEG-4 Audio is audio/mp4.
What file extension does MPEG-4 Audio use?
MPEG-4 Audio files use the .m4a extension. The extension is a convention only and does not guarantee the file contents, so combine it with signature and structure checks.