Getting Filetype from file signature

I have a lot of files, without extensions.
They are all media files, mostly png, jpg, mp4, AAC.

I tested with DROID (From The National Archive) if these files can be identified based on file signature. But DROID has no renaming function, because its for analysing, but keeping the files themselves untouched.
When I add an extension, like a jpg, the files work as expected.

Can I use Advanced Renamer to batch add extensions based on filetype?

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Try New Name: <ExifTool:FileTypeExtension>
Apply to: Extension

Seems to work for many filetypes.

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Reply to #2:
Thats .... very powerfull!
Did the trick, thanks.

Next time I ask first before assuming Advanced Renamer cant do something.
Installed DROID and Java JRE, of which I'm not a fan, so glad I can remove it.

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Reply to #3:

To elaborate on my use-case a bit:

Signal has E2E encryption which I appreciate, for not taking part in any AdTech.
But I care about data-portability also, a lot.

I used this to rename the media in the Signal Desktop (Windows 10) folder.

The files in C:\Users\ ... \AppData\Roaming\Signal\attachments.noindex:
- dont have encryption
- have garbled names
- have no extension.

The methods are:

method0000=methodname:"newname"; active:"1"; mask:"<ExifTool:FileTypeExtension>"; tagpage:"6"; applyto:"extension";

method0001=methodname:"newname"; active:"1"; mask:"<Year Modified><Month Modified><Day Modified> - <Hour Modified><Min Modified><Sec Modified> - Signal - <Inc Nr:1>"; tagpage:"5"; applyto:"name";

After this I can do all sorts of handling, for archiving purposes.

Took a while to load 8k files and renaming them but works perfect!

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