Thumbnails disappearing; not rebuilding

[Noah Kadner]

I’d do a preferences reset and clear out renders.

Noah

FCPWORKS – FCPX Workflow
Call Box Training

[Mike Bonner]

Oh, I forgot to mention:
I deleted the cache, trashed preferences, and trashed plists.
I also see now that I have a few clips in a multicam clip that show up black, playback black, but audio is audible. Original clips play fine in the Finder.
Ugh.

[Noah Kadner]

I’d try deleting the FCPX app and redownloading from the App Store.

Noah

FCPWORKS – FCPX Workflow
Call Box Training

[Mike Bonner]

Very strange. Like I said, I had problems with disappearing thumbnails. I use two identical drives that I will work off of from work and at home, transferring the library whenever I make a change. The project at my work machine didn’t experience any problems, but my portable drive gave me the problems I described. As a test I plugged my portable drive into my work computer, and low and behold, there were two clips that came up black. Checking the files in the finder, they played back fine. I tried reconnecting, deleting and replacing, trashing the cache, but each time they would come up black. Finally, I copied the event into a new library, and they were back. This is discouraging because I had a problem on a different project exporting, and it too was solved by creating a new library. So, libraries corrupting? But, this seems strange as I delete and replace the old library everyday just before going home.

[Doug Metz]

Hmmm… that is a bit strange. Two questions:

Are both drives formatted the same?

Are both drives ignoring ownership? Sometimes plugging in a drive to a different machine can cause this setting to become unchecked – not sure why.

Doug Metz

Anode

[Mike Bonner]

Yeah, both Mac Extended Journaled, both ignoring ownership.
I am reformatting the portable drive and repopulating. See if that helps.

[Bernat Garrigos]

Mike,

I have exactly the same problem. Did you finally solve it?

[Joe Marler]

I also had the same problem. In my case Spotlight indexing was disabled on the media drive. When I re-enabled this and allowed time for the indexes to rebuild, FCPX browser thumbnail generation became much faster on large events.

Disabling Spotlight on media drives is a common recommendation and maybe a good idea in some cases. However for very large events with thousands of clips, it appears Spotlight somehow accelerates thumbnail generation. I think it’s ultimately a bug in FCPX since thumbnail generation would not just slow down, but would stop completely unless Spotlight was enabled.

There is still some initial lag on huge events (7000+ clips), and Activity Monitor indicates very high I/O rate (15,000 I/Os per sec on my 16TB RAID) but after they are generated it is very fast, even after selecting different thumbnail heights. If I select longer thumbnails (not just single frame) those must generate as I scroll down, but afterwards it remains fast — even after rebooting.

Unfortunately there is no way to tell FCPX to proactively generate them — you have to scroll down. The UI is somehow sending messages to the thumbnail generation thread. This is probably an optimization to avoid a lengthy thumbnail/preview generation period as with LightRoom, etc.

There may be multiple causes of this behavior. I first tried deleting the thumbnail files in the Library, which did not help. In my case it was unique to thumbnail mode in the Event Browser — list mode never had any problem, and thumbnails always appeared in the timeline.

I have 7,000+ clips (many 4k H264) and over 4TB in one event on a top-spec 2015 iMac 27 and 16TB Thunderbay 4, and it works very well. It is amazingly fast after the thumbnails are generated.