.AVI file signature

A Audio Video Interleave file begins with the bytes 52 49 46 46 ?? ?? ?? ?? 41 56 49 20 (RIFF....AVI in ASCII) at the start of the file. The signature is the same whatever the file is named, which is why a renamed or extensionless AVI file is still recognisable.

Signature

Offset	Hex	ASCII
0	52 49 46 46 ?? ?? ?? ?? 41 56 49 20	RIFF....AVI

MIME type: video/x-msvideo · usual extensions: .avi

How to check a file's signature

Without installing anything: drop the file on our detector. It reads the bytes in your browser and shows the hex dump alongside the verdict; nothing is uploaded.

macOS and Linux (Terminal):

xxd -l 32 file.avi
file file.avi

Windows (PowerShell):

Format-Hex -Path file.avi -Count 32

If the bytes do not match

A file named .avi whose first bytes are something else is not a AVI file. The common explanations are a wrong or deliberately misleading extension, a download that saved an HTML error page instead of the file, or a container such as ZIP wrapping the real content. The detector reports what the bytes say; the AVI guide explains what a genuine file should contain.

What is .AVI file?All file signatures