The “Analyze” button does NOT generate preview and chapter thumbnails. The Analyze function only analyzes the media characteristics (bitrate, filesize, etc etc) and updates as necessary. Analyze is not synonymous with thumbnail generation. For example, if I upload an updated version of a movie which has a different bitrate, I press “Analyze” and the media characteristics are updated. The analyze button has nothing to do with thumbnail generation.
HOWEVER
It just happens that for some people it seems to jumpstart thumbnail generation almost as an aside, but that’s not what the function is designed to do. Unfortunately, over time, people have come to equate pressing “Analyze” with thumbnail generation so many answers say “just press analyze,” but that’s not what analyze is meant to do.
It is documented to initiate generation of VPTs:
I’m still trying to figure out if the hidden and off-by-default GenerateIndexFilesDuringAnalysis setting does anything.
I have reported an issue where auto generate the video thumbnails a while ago here Video preview thumbnails are no longer being generated automatically . I’m posting on this thread since I now have another issue with generating the thumbnails.
If I remove a library (I’m upgrading it from SD to HD), in other words, deleting a library such as Friends which I recorded on TV originally and then deleting the thumbnails via ‘troubleshoting - clean bundles’ and then replacing the series with the new purchased blurays, the thumbnail genrates only one or two frames for each episode.
Does anyone have any idea on how to fix this?
That may indicate an encoding problem with the new DVDs. Can you share your logs and/or one of the video files?
Changing this hidden Plex setting might allow thumbnail generation to complete:
Video Preview Thumbnail Generation Fails for Some Items - #48 by Volts
Looking at that sample, I’m not sure if it’s EXACTLY the same issue as from the other thread. But it’s definitely related to the video’s structure/GOP/keyframes.
But I can confirm the same behavior you see, and I can confirm that enabling that GenerateBIFKeyframesOnly hidden preference will enable Plex to generate thumbnails for this file.
Look at the link above, and here for more details about how to do it.
Hi Volts, Yep! That fixed the issue. Thank you so much for your support.
The original issue - that of video preview thumbnail generation stopping working and needing to be turned off/on in the settings, or PMS restarted, to get it going again - seems to have finally been fixed with the latest update. I’ve had it running for over 24 hours now, and thumbnail generation - both automatic and manually triggered - is still working fine.
This issue appears to be fixed for me as well. I have not restarted Plex Media Server or changed the settings for several days and the preview thumbnails have been generating automatically for newly added content.
Setup:
Mac Mini 2012 running Mac OS Catalina 10.15.7
Plex Media Server Version 1.23.4.4712
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