How does thumbnail preview in Ubuntu differ from that of Windows?

I thought this question might get a better response in AskUbuntu, as it seems to have more to do with Ubuntu than Windows at a glance.

Let's say I have a foo.mkv file. Thumbnail previews work in both Windows 7 and Ubuntu.

When I change the filename to anything random like foo.bar or when I remove the extension itself (making it just foo), Nautilus shows thumbnails normally like if it can recognize what type of files they are - without looking at file extension.

This however, doesn't happen in Windows 7. Windows starts asking me things like which application I want to use to open that file as soon as I remove file extension (forget thumbnails...) etc.

So, How does this thumbnail preview work in Windows 7 and Ubuntu? What makes Ubuntu recognize files "out of the box" unlike Windows 7?

Solution 1:

I think Ubuntu uses the file header to identify file type and generate the thumbnail on that basis , but in windows a file containing meta data named Thumbnail.db would be updated when windows explorer scan file types (based on the file extension).

This document supports my answer . http://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html#CREATION

Ubuntu uses Nautilus that complies with Freedesktop implementation, that uses file MIMEtype . Visit above link for more specifications.