Flash video file (.flv)
.flv file signature | video/x-flv
Flash Video (FLV) is a container format developed by Adobe Systems for delivering video and audio content in the Adobe Flash platform. It was widely used for web video streaming, embedded media players, and online video sharing in browsers that supported Flash. FLV is now largely a legacy format following the decline of Adobe Flash, and files should be handled cautiously because media containers can still carry malformed or malicious payloads.
Magic Bytes
Offset 0
46 4C 56
Sources: Apache Tika, Wikipedia, Neil Harvey FileSignatures
All Known Signatures
3 signature variants are documented for .flv files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 46 4C 56 | 0 | Apache Tika, Wikipedia, Neil Harvey FileSignatures |
| 46 4C 56 01 | 0 | Gary Kessler |
| 66 74 79 70 4D 34 56 20 | 4 | Gary Kessler |
Extension
.flv
MIME Type
video/x-flv
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .flv files in Python
def is_flv(file_path: str) -> bool:
"""Check if file is a valid FLV by magic bytes."""
signature = bytes([0x46, 0x4C, 0x56])
with open(file_path, "rb") as f:
return f.read(3) == signatureHow to validate .flv files in Node.js
function isFLV(buffer: Buffer): boolean {
const signature = Buffer.from([0x46, 0x4C, 0x56]);
return buffer.subarray(0, 3).equals(signature);
}How to validate .flv files in Go
func IsFLV(data []byte) bool {
signature := []byte{0x46, 0x4C, 0x56}
if len(data) < 3 {
return false
}
return bytes.Equal(data[:3], signature)
}API Endpoint
/api/v1/flv
curl https://filesignature.org/api/v1/flv
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .flv file?
A .flv file is a Flash video file file. Flash Video (FLV) is a container format developed by Adobe Systems for delivering video and audio content in the Adobe Flash platform. It was widely used for web video streaming, embedded media players, and online video sharing in browsers that supported Flash. FLV is now largely a legacy format following the decline of Adobe Flash, and files should be handled cautiously because media containers can still carry malformed or malicious payloads.
What are the magic bytes for .flv files?
The magic bytes for Flash video file files are 46 4C 56 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .flv file?
To validate a .flv file, read the first bytes of the file and compare them against the known magic bytes (46 4C 56) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .flv files?
The primary MIME type for .flv files is video/x-flv.
Is it safe to open .flv files?
Flash video file (.flv) 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.