# Generating new chapter thumbnails for weeks **URL:** \ **Category:** Plex Media Server\ **Tags:** server-docker, server-synology\ **Created:** [October 31, 2022, 2:28pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795 "2022-10-31T14:28:22Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![savagenl](https://avatars.discourse-cdn.com/v4/letter/s/f17d59/32.png) [@savagenl](https://forums.plex.tv/u/savagenl)\ **Post date:** [October 31, 2022, 2:28pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/1 "2022-10-31T14:28:22Z")
Server Version#: Latest (4.87.2) Player Version#: Latest Android (9.9.0.35519) For a couple of weeks my Plex running in Docker (plexinc/pms-docker) on a Synology is using up a lot of resources to generate chapter thumbnails. The log files are completely full with “Generated new chapter thumbnails for xxx”, where xxx is a new movie/episode every few minutes or hours. Since this is running for weeks I don’t expect it to end. Any idea what can be wrong? I already tried to: - Move all movies/series, clear/clean Plex data. Then move the files back to trigger the process again. - Reset the Docker image But nothing seems to work… ---
**Author:** ![FordGuy61](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@FordGuy61](https://forums.plex.tv/u/FordGuy61)\ **Post date:** [October 31, 2022, 6:05pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/2 "2022-10-31T18:05:17Z")
Please verify the Plex Media Server version via [Settings](https://app.plex.tv/desktop/#!/settings/web/general) → Server\_Name → General or [Authorized Devices](https://app.plex.tv/desktop/#!/settings/devices/pms). 4.87.2 is the version for Plex Web. Is it just chapter thumbnails or also video preview thumbnails? Video preview thumbnail generation will take some time for each file. Plex creates a thumbnail for every two seconds of video. Moving the movies/series will simply restart the process from the beginning for each file you moved. If desired, you can configure Plex to generate thumbnails only during scheduled maintenance hours. Go to [Settings](https://app.plex.tv/desktop/#!/settings/web/general) → Library. Change `Generate video preview thumbnails` and `Generate chapter thumbnails` to `As A Scheduled Task` (or `Never` to completely disable the process). Thumbnail generation will run during the hours configured in [Settings](https://app.plex.tv/desktop/#!/settings/web/general) → Scheduled Tasks. ---
**Author:** ![FordGuy61](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@FordGuy61](https://forums.plex.tv/u/FordGuy61)\ **Post date:** [October 31, 2022, 7:10pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/3 "2022-10-31T19:10:35Z")
Here’s an example from my system. PMS 1.29.2.6334, native, not in Docker. Synology DS918+, DSM 7.1.1.42962 Avengers: Endgame (2019): 3 hours, 1 minute Preview thumbnail generation begins: 12:47:49 Preview thumbnail generation ends: 13:35:07 Duration: 47:18 One of my movie libraries has ~2600 hours of video. At a preview generation rate of ~15.67 minutes per hour of video, it would take ~7 days to generate thumbnails for all the movies. ---
**Author:** ![savagenl](https://avatars.discourse-cdn.com/v4/letter/s/f17d59/32.png) [@savagenl](https://forums.plex.tv/u/savagenl)\ **Post date:** [October 31, 2022, 8:20pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/4 "2022-10-31T20:20:57Z")
Thanks! My PMS version is 1.29.1.6316. It is running on a Synology 920+ which has hardware encoding enabled, and it takes about 30% of CPU while generating tumbnails. But that is slowing down the whole system. I’m not sure whether it is about chapter or video preview thumbnails, how can I check that? I have about 500 hours of video in total, so that is 5x less than you have, but it is running longer than a week. Generating thumbnails for most episodes take 5-15min, but some also take more than an hour. But quite a big part is 4K HDR, that might make a difference. Either way you already helped me a lot by limiting the generation to the nights. That way it is not disturbing that much, and if there is no easy solution I can let it run for the coming period to see if it stops by itself. ---
**Author:** ![FordGuy61](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@FordGuy61](https://forums.plex.tv/u/FordGuy61)\ **Post date:** [October 31, 2022, 9:39pm UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/5 "2022-10-31T21:39:55Z")
> [@savagenl](#): > > I’m not sure whether it is about chapter or video preview thumbnails, how can I check that? Chapter thumbnails should be quick, just a two or three minutes per movie. The Activity icon in [Plex Web](https://app.plex.tv/desktop/#!/) will have a spinning circle when either is being generated. If you click on it you’ll see the activity listed. It will say something like “Generating chapter thumbnails for _movie\_name_” or “Generating video preview thumbnails for _movie\_name_.” You can also see the activity `Plex Media Server.log` file: Video preview thumbnails are easy to spot because there’s an entry for every 0.1% of progress. 🤣 If you search for the activity string, you can find the start/stop times. Video Preview Thumbnails ```auto Oct 31, 2022 12:47:49.377 [0x7f1fd70dbb38] DEBUG - Activity: registered new activity e61fbb38-8de0-4e5b-bc50-abe35236ec8b - "Generating video preview thumbnails" (Memory Usage: 56.0 MB/1352.0 MB) ... Oct 31, 2022 12:53:13.627 [0x7f1fd67f8b38] DEBUG - [Req#964/Transcode/bif/e61fbb38-8de0-4e5b-bc50-abe35236ec8b] Activity: updated activity e61fbb38-8de0-4e5b-bc50-abe35236ec8b - completed 10.3% - Generating video preview thumbnails (Memory Usage: 66.0 MB/1545.0 MB) ... Oct 31, 2022 13:35:07.053 [0x7f1fd70dbb38] DEBUG - Activity: Ended activity e61fbb38-8de0-4e5b-bc50-abe35236ec8b (Memory Usage: 67.0 MB/1262.0 MB). ``` Chapter Thumbnails ```auto Oct 31, 2022 12:47:49.361 [0x7f1fd72deb38] DEBUG - Activity: registered new activity 9629cff4-dbc7-45f0-ac45-df28da0768db - "Generating video chapter thumbnails" (Memory Usage: 56.0 MB/1350.0 MB) ... Oct 31, 2022 12:50:35.692 [0x7f1fd72deb38] DEBUG - Activity: Ended activity 9629cff4-dbc7-45f0-ac45-df28da0768db (Memory Usage: 58.0 MB/1545.0 MB). ``` ---
**Author:** ![savagenl](https://avatars.discourse-cdn.com/v4/letter/s/f17d59/32.png) [@savagenl](https://forums.plex.tv/u/savagenl)\ **Post date:** [November 1, 2022, 7:31am UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/6 "2022-11-01T07:31:39Z")
I’ve now set the tasks (video preview and chapter thumbnails) to run between 0:00 and 9:00, but I don’t see that back in the logs. I am however a bit surprised by the number of errors and warnings in the log (see attached). Many problems with transcoding/decoding, metadata, XML, etc ---
**Author:** ![system](https://global.discourse-cdn.com/plex/original/3X/2/a/2acb9765406f63293d357b4ec509ec39aa28f2ad.png) [@system](https://forums.plex.tv/u/system)\ **Post date:** [January 30, 2023, 7:31am UTC](https://forums.plex.tv/t/generating-new-chapter-thumbnails-for-weeks/816795/7 "2023-01-30T07:31:47Z")
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