3GP file signature
Magic number at offset 4 · ftyp3gp
3GP mobile video is an ISO Base Media file whose ftyp brand at offset 8 begins 3gp (for example 3gp4 or 3gp5). It shares the container with MP4 but uses codecs tuned for mobile networks.
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 contains, at offset 4, the bytes 66 74 79 70 33 67 70 (the text ftyp3gp), it is a 3GP file.
Formats that use the 66 74 79 70 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 -s 4 -l 7 example.3gp
- hexdump -C -s 4 -n 7 example.3gp
- file example.3gp
Windows (PowerShell)
- Format-Hex -Path example.3gp -Count 16
Python
- f=open("example.3gp","rb");f.seek(4);f.read(7).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the 3GP file signature?
3GP files carry, at offset 4, the hex bytes 66 74 79 70 33 67 70 (ftyp3gp 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.3gp on Linux or macOS, or Format-Hex -Path example.3gp -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the 3GP signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine 3GP file has these exact bytes; a file with the wrong bytes is not really 3GP, whatever its name says.