Question - associating artwork with file icons

[True Colors]

mkvtomp4 is a program that I have been playing around with lately. It seems pretty cool.

One feature it has which I especially like is the ability to add artwork to an MP4 file. That way, when you look at it in Windows explorer the icon actually looks like the artwork.

So my question is this...... how exactly does this work?

I could be wrong, but I seem to recall an explanation on this. Something about how Windows explorer generates the icon image by pulling a single frame from within the video file, and mkvtomp4 knows which frame number that Windows pulls, so it inserts your artwork image there.

Is this correct? If so, does anybody know which frame number is used for this purpose?

Any insights that you can provide in this matter will be greatly appreciated.

Thanks!

TC

[JVRaines]

More likely mkvtomp4 is pulling the frame from Windows' thumbnail cache. As far as I know, Microsoft's video thumbnail algorithm has not been published or reverse engineered.

[johns0]

I haven't used mkvtomp4 but video files can contain image files,i've used mkvmerge to remove them.

[theewizard]

GAWD
its been ages since i played around with anything like that
but there used to be a program out there for creating custom ICONS, you could open any file and change the icon
as said the icons for most files are assigned by windows , according to what program opens them
the icon program, would replace the cached ICON image with the custom one
it used the file only for reference to find the one in windows ICON cache, it did NOT actually modify the original file

[True Colors]

I found an article which explains this topic much more clearly than what I am able to do:

http://www.makeuseof.com/tag/7-hidden-windows-caches-clear/

4. Thumbnail Cache

Windows has a setting that allows for thumbnail previews of files. For example, when enabled, an .MP4 video file will be shown with a frame from the video itself while a .PNG image file will be a preview of what the image looks like.

Thumbnails are great from a usability standpoint, but where do you think those thumbnails come from? Windows has to generate them on demand. When you use File Explorer to browse folders, every time you encounter a file for the first time, Windows has to create a thumbnail for it.

In a manner of speaking, Microsoft Windows pulls a frame from the video and uses it to create a thumbnail cache image which is associated with the video file.

From what I can tell, it is a hidden frame from the video which is used to create the thumbnail image for the video file. I say this because I have a video editor which allows me to go frame by individual frame(VideoRedo). I used this to try to locate the frame which was being used to create the thumbnail image but it cannot be found.

I guess what I am looking for is a thumbnail cache editor maybe?

Anyway, if anyone has any thoughts/ideas/suggestions, then I am all ears.

Thanks,

TC