Video Preview Thumbnails don't seem to work on the web app

[brothom 177]

Thanks a bunch guys! With Emby 4.9.1.80 we can finally (or more like apparently?) create seek previews/Video Preview Thumbnails so that we see what happened whilst seeking without having to stop! This feature works great on my Samsung Smart TV.

However, the preview functionality doesn't seem to work on the web app since that only shows the time at that point. 

Note: Is this still a work in progress, because I didn't see the preview functionality being mentioned other than it suddenly being available, being able to activate it and it working on my TV.

[Luke 42077]

HI there, can you please provide a specific example?

How to Report a Problem

Thanks !

 

[brothom 177]

Wait this is weird. The same file that showed previews while seeking just yesterday, isn't doing that anymore?
I just tried reproducing it on my TV to provide an example but seeking on my TV suddenly doesn't show any previews anymore. 

For Star Trek Strange New Worlds Season 02 my chapters are set wrong (Emby's default of every 5 minutes) but that obviously doesn't match up with when the intro is shown within the episodes.
So I started seeking and to my suprise, I could see previews and could locate when the intro was over (the logo of the show would be shown in the preview) and stopped playback there which matched up exactly.

Another weird thing is that I remember the files being filename.bif, but now they're filename-320-10.bif.

The feature to preview the current media from the seek bar has been added right?
I'm sorry, but am I high or something? Was I hallucinating? I hope not.

Edited October 2, 2025 by brothom

[Luke 42077]

Quote

Another weird thing is that I remember the files being filename.bif, but now they're filename-320-10.bif.

The server supports filename,bif and may have saved it that way a long, long time ago, but at some point that was changed to add the resolution and frequency into the file name.

[Luke 42077]

Quote

The feature to preview the current media from the seek bar has been added right?

I'm not sure what you mean. The answer is yes, but it's not a new thing.

[brothom 177]

8 hours ago, Luke said:

I'm not sure what you mean. The answer is yes, but it's not a new thing.

Okay so, just to make sure; by configuring the "Video Preview Thumbnails" section in a library, `.bif` files are created that contain previews (per configured interval) which are then use to create a preview of the media within the player during seek operations.

This "video preview when seeking" (apparently, but only once?) worked on my Samsung Smart TV (tizen), hence my suprise.
But after reorganizing my files it apparently stopped working.

The bif file is generated by Emby and I haven't changed the media either, so my questions:

Is this Video Preview also supposed to work within the Emby Web app?
I checked to see if the resolution-interval.bif file exists, and it does.

But when using the web app for that media, it only shows the current seek time, not a preview of the media at that time: 

Is the Video Preview even supposed to work on the Emby Samsung Tizen app?

I've never seen this functionality before or at least it never seemed to work until a day ago.

[Luke 42077]

Hi, yes it already works with both the web app and Emby Samsung apps.

[brothom 177]

On 05/10/2025 at 04:07, Luke said:

Hi, yes it already works with both the web app and Emby Samsung apps.

Strange, I wasn't able to get this feature to work again in the web app or the Samsung tv app. I can see the biff files appear and have set them to be saved alongside the media as a test, but still not video previews somehow during seeking within the webapp or my Samsung tv.

I have these settings, that should be sufficient for this feature to work right?

[brothom 177]

@LukeI think I may have figured out what's going on.

1. Went to a show/season
2. Removed all old bif files
3. Refreshed meta data (replace existing video preview thumbnails)
4. Waited for the bif-files to reappear
5. Opened that show/season in Emby
6. Previews are now working

I think something might be up when a .bif file is generated for a filename, but both file names are changed when moving the file, or when a bif file has been previously generated for another version.

This case seems to be "going wrong" regardless:

1. add media "finding-nemo.mkv"
2. a bif file named "finding-nemo-320-10.bif" is added
3. rename media to "Finding Nemo (2003).mkv"
4. rename bif file to "Finding Nemo (2003)-320-10.bif"
5. previews are no longer displayed
   (my hunch is that it's because the bif file's location doesn't match the one in the sqllite database?)

[brothom 177]

Okay so I have removed all .bif files for a specific season and regenerated them, but still Emby won't show the previews for them.

I can see Emby is returning thumbnails in the URL "/emby/Items/27766/ThumbnailSet"

{
    "AspectRatio": 2.4,
    "Thumbnails": [
        {
            "PositionTicks": 0,
            "ImageTag": "91045e77e7a366a60297f219c81f6c6c"
        },
        {
            "PositionTicks": 100000000,
            "ImageTag": "91045e77e7a366a60297f219c81f6c6c"
        },

But still, seeking will only show me the time.

Actually visting the thumbnail URL (/emby/Items/27756/Images/Thumbnail?maxWidth=400&tag=91045e77e7a366a60297f219c81f6c6c&PositionTicks=100000000&MediaSourceId=mediasource_27756&quality=90) also shows the time at the video.

But for some reason, whilst season 1 of this show has thumbnails, episodes in season 2 just don't seem to "look up" the thumbnail images.

Removing the bif files didn't work. Next I'll try and move the entire folder alltogether to see if that makes a difference. 

[Luke 42077]

On 10/8/2025 at 2:50 PM, brothom said:

Okay so I have removed all .bif files for a specific season and regenerated them, but still Emby won't show the previews for them.

I can see Emby is returning thumbnails in the URL "/emby/Items/27766/ThumbnailSet"

{
    "AspectRatio": 2.4,
    "Thumbnails": [
        {
            "PositionTicks": 0,
            "ImageTag": "91045e77e7a366a60297f219c81f6c6c"
        },
        {
            "PositionTicks": 100000000,
            "ImageTag": "91045e77e7a366a60297f219c81f6c6c"
        },

But still, seeking will only show me the time.

Actually visting the thumbnail URL (/emby/Items/27756/Images/Thumbnail?maxWidth=400&tag=91045e77e7a366a60297f219c81f6c6c&PositionTicks=100000000&MediaSourceId=mediasource_27756&quality=90) also shows the time at the video.

But for some reason, whilst season 1 of this show has thumbnails, episodes in season 2 just don't seem to "look up" the thumbnail images.

Removing the bif files didn't work. Next I'll try and move the entire folder alltogether to see if that makes a difference. 

Yea I would try refreshing the metadata on them and see if that helps.

[brothom 177]

12 hours ago, Luke said:

Yea I would try refreshing the metadata on them and see if that helps.

Strange. It's as if the files for Season 01 are treated different from the other seasons in my case. 

I've moved all files for all seasons and even generated new downscaled version. Both the original and downscales for Season 01 show the previews whilst Season 02 and 03 don't seems to work at all, despite the API returning the ThumbnailSets.

After some searching I also noticed that some scheduled tasks have been out of wack, maybe that's because I switched over to starting Emby as a service. I'll let the Scheduled Task for Thumbnail Preview do a full run which is already at it for two days but that's to be expected I suppose.

When the run is done I'll manually refresh the Video Thumbnails for the items that aren't working and if they still don't show the previews then I'll report back.

Thanks for your time so far @Luke

[brothom 177]

@Lukeso I refreshed my entire library but for some reason, Season 02 and 03 for this specific tv series won't show the video preview thumbnaisl whilst scrolling.

Manually refreshing the item led to this output:

2025-10-12 16:08:29.007 Info ProviderManager: RefreshItem Start: 92509 Episode G:\Media\Series\Star Trek Strange New Worlds (2022)\Season 02\UHD\Star Trek Strange New Worlds - s02e01 - The Broken Circle - 4K.mkv
2025-10-12 16:08:29.010 Info MediaProbeManager: ProcessRun 'ffprobe' Execute: C:\Users\User\AppData\Roaming\Emby-Server\system\ffprobe.exe -i file:"G:\Media\Series\Star Trek Strange New Worlds (2022)\Season 02\UHD\Star Trek Strange New Worlds - s02e01 - The Broken Circle - 4K.mkv" -threads 0 -v info -print_format json -show_streams -show_chapters -show_format -show_data
2025-10-12 16:08:29.083 Info MediaProbeManager: ProcessRun 'ffprobe' Process exited with code 0
2025-10-12 16:08:29.110 Info HttpClient: GET https://api4.thetvdb.com/v4/episodes/9697914/extended?meta=translations
2025-10-12 16:08:29.312 Info HttpClient: Http response 200 from https://api4.thetvdb.com/v4/episodes/9697914/extended?meta=translations after 201ms
2025-10-12 16:08:29.320 Info QuickImageSeriesExtractor: ProcessRun 'quick-extract-imageseries' Execute: C:\Users\User\AppData\Roaming\Emby-Server\system\ffmpeg.exe -f matroska -threads 1 -skip_interval 10 -i file:"G:\Media\Series\Star Trek Strange New Worlds (2022)\Season 02\UHD\Star Trek Strange New Worlds - s02e01 - The Broken Circle - 4K.mkv" -an -sn -vf "scale=w=320:h=133" -f image2 -b:v 100M "C:\Users\User\AppData\Roaming\Emby-Server\programdata\cache\temp\12db4533ac624176aee1a62fa89a48b1\img_%05d.jpg"
2025-10-12 16:09:41.356 Info QuickImageSeriesExtractor: ProcessRun 'quick-extract-imageseries' Process exited with code 0
2025-10-12 16:09:41.499 Info ProviderManager: RefreshItem Complete: 92509 Episode G:\Media\Series\Star Trek Strange New Worlds (2022)\Season 02\UHD\Star Trek Strange New Worlds - s02e01 - The Broken Circle - 4K.mkv

The .bif file has a changed "modified at" date, but still the seek bar only shows the time.

Has previews:

no previews

also no previews

At first I thought it might've been the SUBRIP subs, but I also found other episodes that have them and still have previews. Forcing regeneration or running the scheduled task both don't seem to solve the issue and as previously mentioned, the files do seem to be created properly.

Is there anything else I can try?

[Luke 42077]

But other seasons do?

[brothom 177]

16 minutes ago, Luke said:

But other seasons do?

Strangely Season 01 is fine. Season 02 doesnt work at all and the second half of Season 03 works again. Almost as if those entries are messed up somehow.

I havent noticed issues with other seasons yet and tried to check if they had this issue but couldnt find any so far.

What I might want to do is actually "move" the broken entries outside of the library, let Emby scan (and delete the entries) and add them back in to see if Emby will treat the "new" entries differently.

Will do that later.

Edited October 13, 2025 by brothom

[brothom 177]

Okay so I moved Season 02 out of the library, waited for it to be scanned and removed and added it back in.
That didn't seem to help, the Season itself still had the same "played" marks (since I had already viewed all episodes in this season) so I'm pretty sure Emby didn't remove the media entries when I removed the folder.

Also rescanning / refreshing metadata/previews doesn't do anything; no previews are shown, unless they're for episodes that previously already had the previews working strangely enough.

@LukeIs there a way to "hard delete" items from Emby, without deleting the files?
I want to see if there's something up with the media files themselves that prevent the previews from working or if it's a database issue.

[Luke 42077]

Quote

@LukeIs there a way to "hard delete" items from Emby, without deleting the files?

No, but maybe try adding a whole new series altogether?

[brothom 177]

On 15/10/2025 at 17:33, Luke said:

No, but maybe try adding a whole new series altogether?

I did some additionls tests and new and old entries seem to work accordingly, with the exceptions of episode s02e01 up until s03e05 oddly enough. It's like that whole chain of entries has some underlying issues with generating the previews. 

Any other clues?

[Luke 42077]

Nothing comes to mind. did you find anything?

[brothom 177]

On 26/10/2025 at 05:58, Luke said:

Nothing comes to mind. did you find anything?

No, not yet. New entries seems to work fine. Other entries that were generated before, moved/renamed and generated again seem to work properly as well. It's almost as if the entries within this season/show are "different".

The only thing I can think of is to literally delete the items from the library and wait until Emby has removed the databased entries (if it even does that?) and once permanently deleted, add them back in. It's not a workaround but I have the feeling it has to do with the existing entries.

Edited October 27, 2025 by brothom

[Luke 42077]

Hi, are you still having an issue with this?

[brothom 177]

11 hours ago, Luke said:

Hi, are you still having an issue with this?

Some episodes still display no thumbnails, whilst they are generated and the browser makes the request to `emby/Items/92744/ThumbnailSet?MediaSourceId=mediasource_92735&` which in returns a bunch of thumbnails:

 

None of them are displayed within the player, when seeking just the time is shown instead of also the previews.

So same as far; new entries seem okay but a bunch of my old entries still don't/can't/won't show the video preview thumbs.