Replacing thumbnail on .mkv file using mkvtoolnix or mkvmerge

[PeterProg]

Hi

Newbie question. I recently downloaded an mkv file with no thumbnail attached / embedded. I wanted to add a thumbnail and after a bit of googling, I discovered that I could add a thumbnail using mkvtoolnix. I grabbed a couple of screenshots from the file (saved as jpgs). Tried the first jpg (merging it into the mkv via the Attachment tab in mkvtoolnix) and all went well. Thought it looked quite good, but thought I might try the second jpg as well and see how that looked.

That's where the fun started. No power on earth can seem to shift the original jpg that I merged into the file. I've gone back to the original mkv file with no thumbnail / jpg attached and repeated the same process in mkvtoolnix with the second jpg as I did with the first. Muxing the file yields the original jpg thumbnail. I've gone into the muxed file, Attachments tab, disabled the embedded jpg and added the new one, remuxed, same result. I renamed the second jpg, added it to the original file with no thumbnail, muxed it, same result even though under the Attachments tab, the renamed file appears as the relevant attachment. I even emptied the thumbnails cache on the PC, but no effect - I seem to be stuck with my original thumbnail.

I read that I might be able to do something in mkvpropedit, but I could see no GUI in the mkvtooknix folder and couldn't figure out anyway to run / use mkvpropedit.

I am thinking there must be some way within the mkvtoolnix toolset to edit or replace an mkv thumbnail, but I cannot see it at the moment. Any suggestions gratefully received.

Cheers

[ndjamena]

right-click->remove attachment works for me.

Then I can replace it with whatever I want.

Windows 10 even updates the thumbnail on the fly so it's always showing whatever is in the file (or a screenshot from the video track if there's no image).

Are you naming them cover.jpg.

How are you seeing the thumbnails (codec pack/program)?

[PeterProg]

Many thanks for getting back to me. I've also got Windows 10.

I have the mkv file sitting on my desktop, but if I right-click, I don't get a remove attachment option. Do you mean right-clicking on the file title from within mkvtoolnix, or in some other context? 'Remove attachment' would be far and away the best outcome if I could find how to get to that point!

I didn't name the original file cover.jpg - it was simply a jpg screenshot from the file with a random name - but having done a bit of reading trying to resolve my issue, I did name the screenshot that I am trying to replace it with cover.jpg. But it is still not over-riding the original.

I haven't installed any particular codec packs or programs in recent times - the file is simply displaying the thumbnail in Windows 10. I did have a look at the file on my old PC running Windows 7 and I did note that the thumbnail was not displaying there.

[PeterProg]

PS If I right-click on the thumbnail file name under the Attachments tab in mkvtoolnix, the options I get are to enable or disable the selected attached file(s). Selecting the disable option should do it, but again after muxing the file, the original thumbnail remains stubbornly in place.

[ndjamena]

What you want is the header editor, not the multiplexer.

It's on the desktop... are you sure what's being displayed is the one you created and not the thumbnail windows is generating from the video track?

I'm not sure Windows 10 can interpret Mastroska cover.jpg attachments by default, you may have to install a codec pack (or whatever) to get it working. But make sure that's the actual problem before considering that.

[Krispy Kritter]

Open the file in MKVToolNIX, you should see a list of the contents, one of which should be the cover. To the left of the file contents is a check box, uncheck the items which you don't want (in this case, the cover), change the output file name and click "Start muxing". You will end up with a file without a cover. If you want to add a different cover, you simply add the mkv created above and the new cover into MKVToolNix and mux them together.

[ndjamena]

Remuxing the entire file is a really inefficient way of removing or adding a single image attachment.

The attachment editor in the header editor has been there for a while, and can add and delete these things in an instant without having to recreate the entire file.

[PeterProg]

Thanks guys for your responses.

I am beginning to think that the issue is fundamentally a function of how mkvtoolnix is interacting with Windows 10. I have tried both steps - both gone into the header editor and removed the attachment and multiplexed the whole file having disabled the attachment. After removing the attachment, the original thumbnail still displays after saving the change. After multiplexing, the original thumbnail still displays as ever despite the fact that reviewing the new file in mkvtoolnix, there is nothing listed under the Attachment tab. However, what makes the whole issue a puzzle is that the original file I downloaded, which had no thumbnail - the whole reason I went to mkvtoolnix in the first place to add a thumbnail - still displays in Windows 10 with no thumbnail. It is only the file versions I have treated in mkvtoolnix - either to add or attempt to remove the jpg - that display the immovable thumbnail.

I fired up my old PC running Windows 7 and note that none of the versions at all display a thumbnail, whether there is a cover.jpg listed under the Attachment tab or not, so it is clearly a Windows 10 issue.

Also, the immovable thumbnail is not from the opening frames of the file, it is definitely the first screenshot jpg that I muxed a couple of days ago. So it is not something that Windows 10 has initiated or found, it is a product of the muxing with mkvtoolnix. As I say, the original unmuxed file displays no thumbnail at all. I wonder if there is somewhere in Windows 10 that I can go to identify and delete the thumbnail that is over-riding the mkvtoolnix edits?

Appreciate any thoughts, cheers.

[ndjamena]

Thumbs.db is a hidden file put in every folder with files that need thunbnails, it contains windows only copy of the folders thumbnail cache. If you delete that and the problem persists then something is seriously off.

Have you tried putting the file in a different folder or remuxing it somewhere else with a different name? They are different files and there's no way Windows should be giving thumbnails to files that they don't belong to.

If you're willing to take the risk:
https://www.videohelp.com/software/Win7codecs

I've never had a problem with it but you may have something installed on you computer that will conflict with it.

[dannyboy48888]

it is a windows issue, I tried direct show filters but got nothing, the MP4 files the I made with mkv2mp4 or I tag with metaX do it correctly oddly enough, in Ubuntu(Linux) my thumbnails always show for MKV or MP4 as long as I make sure the attachment is cover.jpg

[PeterProg]

It does seem to be a Windows issue. I've remuxed the file in several different folders, with different names but it seems nothing will shift the original jpg. I even did a System Restore to wind windows back a couple of days before I first put the file through mkvtoolnix, and then muxed the original file with no thumbnail along with my preferred cover.jpg. But still, the result was the original thumbnail!

I have yet to try the different Codecs, but will give that option a go as well.

Mkvtoolnix clearly does the job in terms of adding a thumbnail to an mkv file where none exists, but I think the moral is that if adding a thumbnail via mkvtoolnix in windows, choose carefully because you will only get one shot!

Many thanks for the advice and suggestions, much appreciated.

[ndjamena]

It sounds like user error to me.

If you take a file, remux it into a different folder with a different name, then there's absolutely nothing connecting one file to the other and there's no reason AT ALL they should be given the same thumbnail.

Unless of course somehow you've given that icon to anything with the mkv extension, but you're insisting on something else more specific...

But really, there's more going on then you've mentioned and there's not much point in anyone throwing random guesses around.

[PeterProg]

OK - there have obviously been a couple of minor mis-steps.

My initial step in embedding a thumbnail into an mkv file that previously had none was to use an old GUI version of mkvmerge that I have had for a while - mkvmerge GUI v5.8.0 ('no sleep / pillow'). Mkvmerge is now included within later versions of mkvtoolnix of course. This mkvmerge GUI seems to have all the same basic features as the later versions embedded in mkvtoolnix but has been superceded, so maybe this could be an issue. However, in this version of mkvmerge, I simply opened the original file via the 'add' button under the Input tab, added the initial jpg via the 'add' button under the Attachments tab and muxed the file with a new name in a new folder. That produced a file with a thumbnail where there had been none before. I did nothing else in terms of muxing, naming or saving.

Second, I did not rename the jpg prior to embedding it as as part of this muxing process in mkvmerge, I just left the file name associated with the screenshot that I downloaded from the site where I obtained the original file. All the advice seems to be to rename the jpg to cover.jpg, so that may be an issue. For the record, that original jpg file name was devil01.

When I view the originally downloaded file - the one with no thumbnail - in mkvtoolnix, obviously there is no attachment showing up under with the Attachments tab or if viewed via the Edit Header feature, nothing appears there under the Attachment heading. No surprise there. If I look at the the output of the file that I muxed, now with the thumbnail, the relevant file appears both under the Attachments tab and inside the Edit Header feature. The file is called devil01.jpg. Again, no surprise there.

Next if I go into the Edit Header feature, remove the devil01.jpg attachment, save and exit, there is no more attachment appearing in this listing in the output file, but the file still displays the original thumbnail. If I go in and remove the attachment under the Attachments tab and mux, again when looking at the output, there is nothing listed under Attachment, but the file still displays the original attachment. Using either method, if I add my now preferred replacment jpg to either the original file with no thumbnail, or the file that I first treated to add the devil01.jpg, devil01 disappears from the Attachment listing to be replaced by cover.jpg, the replacement file, but again the output under either method displays the original thumbnail.

Looked at on my Windows 7 PC, no thumbnail appears on any file at any stage. In Windows 10, no matter what attachment is listed in the output file, or even if no attachment is listed in the output file, the only thumbnail that displays is the first jpg that I added with mkvmerge, devil01.jpg.

I can see now why I am not having any success in trying to replace this intial thumbnail with a different thumbnail in mkvtoolnix. It seems that somehow Windows 10 has captured the original devil01.jpg that I added, storing it in the file, and no amount of editing in mkvtoolnix is going to shift it. Nothing under video, audio, subtitles or tags that appears in mkvtoolnix when the file is opened reflects this thumbnail.

Clearly, however that thumbnail ended up being captured by a Windows 10 process, nothing I edit in mkvtoolnix is going to shift it. I am sure the issue therefore is: where can I go in Windows 10 to remove this thumbnail that has become associated with the file as a result of my initial effort in mkvmerge? Any suggestions appreciated.

[sneaker]

Try: https://www.tenforums.com/tutorials/5655-thumbnail-cache-clear-reset-windows-10-a.html

[PeterProg]

Thanks - that's a very neat program, but it still didn't shift the image that displays with the file. As an experiment, I remuxed the file once again with my preferred jpeg, and when I analyse the output in mkvtoolnix, the preferred jpeg is the only file listed under Attachment, so I can only assume that the original jpg has, under Windows 10, been allocated some othe status. It is a puzzle for sure.

[sneaker]

Is your explorer set to show hidden files? Sometimes the thumbs.db is directly in the folder. I don't know when exactly.

[iAreSpellWell]

Same path / file viewed from my Win10 Pro (via TeamViewer for easy sreenshot) machine & macOS machine. Attached poster.jpg (though I usually rename it cover.jpg). This is what I get from Win vs Mac. I use Windows regularly, but more things just work automatically on macOS - plain and simple. I would like it to appear the same way in Windows as well....but oh well.


[Attachment 40871 - Click to enlarge]

[PeterProg]

I feel a bit the same. Never could find a fix for my issue with the thumbnail in Windows 10. One day.....