Where are the thumbnails for video tracks stored?

[Jim Curtis]

Mine are all messed up, and trashing prefs, previews, and media caches aren't forcing Pr to rebuild them.  I even re-installed Pr 12.1.2 (OSX), and no luck.

BTW, Pr stores caches elsewhere besides the destination the user specifies in the Preferences, if changed by the user.  On Mac, they're in the root>User>Library>Application Support>Adobe>Common>Media Cache Files folder (which is the default location if you don't change it). 

When I first discovered this, there were tens of thousands of cache files that are ignored by the Delete Cache function in Preferences.  There are also PTX and Peak Files in the Common folder.

I have an alias to the Common folder on my desktop that I use to access it so I can trash all my caches; not just the ones I specified with "Browse" in Preferences.

[Ann Bens]

Under the hamburger dropdown menu in the timeline.

[Jim Curtis]

That's not where they're stored.  That allows you to choose the type, and the Show Video Thumbnails under the wrench allows you to turn them on and off.  Toggling either of those doesn't force them to re-draw.

I want to know where the thumbnails are stored, so that I can delete them and force them to be regenerated.

Seems like this would be a cache thing, as storing thumbnails is primarily what the cache for Bridge does.

Something I just noticed, though, is that turning them off (wrench menu) allows me to scrub my timeline faster, or that is, see more frames in the Program window.  That's good to know.

Come to think of it, the video thumbnails might be loaded into RAM when a Sequence is loaded in the Timeline.

Hmm.  I just noticed that all the clips whose thumbnails are messed up are showing as black when I load them into the Source Window, and they all were clips on which I had applied the Magic Bullet Frames effect, and then removed.  It appears that applying the effect corrupted the source media.  That's bizarre, and calls for more investigation. 

[Jim Curtis]

I just found ANOTHER Media Cache folder:  In the Library>Application Support>Adobe folder, called "OOBE."  But, trashing it didn't help anything.

The more I look into this, the more I think the thumbnails are rendered to the timeline on the fly.

Turns out that all the clips in a certain folder are not showing correctly.  I loaded a b-roll Sequence with dozens of clips, and none of them are showing right.

But, why?  And how do I fix this?

I ran Digital Rebellion's Corrupt Clip Finder on the folder and it reported no corruption.

I started a new Project and imported the old one.  No change.

I re-imported the problem footage into the project again, and dragged them into a new Sequence, and now I see the Thumbnails.  This should be telling me something.

[Averdahl]

AFAIK, those thumbnails are not stored anywhere as they seems to be generated each time one open a project.

I would start with either skipping the alias to the Common folder since it can generate different kind of issues or manually make sure that Premiere Pro does not use that folder.

[Jim Curtis]

Averdahl  wrote

AFAIK, those thumbnails are not stored anywhere as they seems to be generated each time one open a project.

I would start with either skipping the alias to the Common folder since it can generate different kind of issues or manually make sure that Premiere Pro does not use that folder.

Seems you're correct on Part A, but not on Part 2.  I have no choice to skip the Common Folder.  Pr is storing cache files there even though I have chosen another folder for my cache location in the Preferences > Media Cache panel.  I wrote about that in my original post.

[Averdahl]

Seems you're correct on Part A, but not on Part 2

O.k, but have you tested to not use an alias for the Common folder? (Part 2a i wrote about.)

[Jim Curtis · Accepted solution]

Solved, sort of:

I figured out how this went wrong, but not why.  It happened when I did a Modify >  Interpret Footage on a multiple selection of clips in a Bin. 

I fixed the issue by exporting the project as XML and then re-importing it.

Something about Interpret Footage borked my thumbnail previews.