OGG file signature
Magic number at the start of the file · OggS
The Ogg container starts each page with OggS. Whether the payload is Vorbis, Opus or FLAC audio, or Theora video, the outer bytes are the same; Opus files (.opus) are Ogg streams and share this signature.
What this magic number means
A magic number is a short, fixed run of bytes at a known position that tells a program what a file really is, no matter what the filename says. If a file starts with the bytes 4F 67 67 53 (the text OggS), it is a OGG file.
Formats that use the 4F 67 67 53 signature
These file types in our database carry this signature:
How to check a file's signature
You can read the first bytes of any file yourself. The magic bytes are shown in hex, the same way this page lists them.
Linux & macOS
- xxd -l 16 example.ogg
- hexdump -C -n 16 example.ogg
- file example.ogg
Windows (PowerShell)
- Format-Hex -Path example.ogg -Count 16
Python
- open("example.ogg","rb").read(4).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the OGG file signature?
OGG files start with the hex bytes 4F 67 67 53 (OggS in ASCII). This magic number identifies the format regardless of the file's name or extension.
How do I check a file's magic number?
Open the file in a hex editor, or run a command such as xxd -l 16 example.ogg on Linux or macOS, or Format-Hex -Path example.ogg -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the OGG signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine OGG file has these exact bytes; a file with the wrong bytes is not really OGG, whatever its name says.