Video files with long names fail to generate a preview

[gguillemas]

Description

Video files with names longer than approximately 120 characters fail to generate previews. The preview endpoint returns a 500 error code. As far as I can see, the actual reason for the error is not present in any logs. File names of this length are common when serving videos downloaded from Youtube with tools like yt-dlp, which preserve the original title by default.

Expected behaviour

Previews are generated for all compatible video files regardless of the length of their name.

What is happening instead?

The preview is not generated and a 500 error code is returned by the preview endpoint. No errors are logged.

name@server:/tmp$ docker run -it \
  -v ./video.mp4:/srv/80-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/100-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/120-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/140-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -p 8080:80 gtstef/filebrowser
2025/05/23 08:42:29 Initializing FileBrowser Quantum (v0.7.4-beta)
2025/05/23 08:42:29 Using Config file        : config.yaml
2025/05/23 08:42:29 Auth Methods             : [password]
2025/05/23 08:42:29 Creating new database    : database.db
2025/05/23 08:42:29 Sources                  : [srv: /srv]
2025/05/23 08:42:29 Running at               : http://localhost/
2025/05/23 08:42:30 initializing index: [srv]
2025/05/23 08:42:30 Index assessment         : [srv] complexity=simple directories=0 files=4
2025/05/23 08:42:33 GET     | 200 | 192.168.1.150:55813 |              | 0ms          | "/files/"
2025/05/23 08:42:33 GET     | 401 | 192.168.1.150:55814 |              | 0ms          | "/api/users?id=self"
2025/05/23 08:42:35 POST    | 200 | 192.168.1.150:55814 |              | 49ms         | "/api/auth/login"
2025/05/23 08:42:35 GET     | 200 | 192.168.1.150:55814 | admin        | 0ms          | "/api/users?id=self"
2025/05/23 08:42:35 GET     | 200 | 192.168.1.150:55814 | admin        | 0ms          | "/api/resources?path=%2F&source=srv"
2025/05/23 08:42:35 GET     | 200 | 192.168.1.150:55814 | admin        | 0ms          | "/api/jobs/status/sources"
2025/05/23 08:42:35 GET     | 200 | 192.168.1.150:55817 | admin        | 231ms        | "/api/preview?path=%2F80-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4&size=large&key=1747989749453&source=srv&inline=true"
2025/05/23 08:42:35 GET     | 200 | 192.168.1.150:55814 | admin        | 233ms        | "/api/preview?path=%2F100-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4&size=large&key=1747989749453&source=srv&inline=true"
2025/05/23 08:42:38 GET     | 500 | 192.168.1.150:55817 | admin        | 137ms        | "/api/preview?path=%2F120-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4&size=large&key=1747989749453&source=srv&inline=true"
2025/05/23 08:42:39 GET     | 500 | 192.168.1.150:55814 | admin        | 124ms        | "/api/preview?path=%2F140-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4&size=large&key=1747989749453&source=srv&inline=true"

Additional context

This issue triggers when running Filebrowser Quantum with its default configuration and with any compatible video file that I have tested.

How to reproduce?

The bug can be reproduced with this example, which only requires a working video file named video.mp4 in the working directory.

docker run -it \
  -v ./video.mp4:/srv/80-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/100-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/120-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -v ./video.mp4:/srv/140-character-filename-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.mp4 \
  -p 8080:80 gtstef/filebrowser

Once the server is running, visit the interface on localhost, log in with the default credentials admin / admin and verify that previews for 80 and 100 character filenames have been generated whereas those for 120 and 140 character filenames have not.

Files

No specific files. Any compatible video file should trigger the issue.

[gtsteffaniak]

Very much appreciate the detailed info. I have ffmpeg logging disabled even for video, maybe I'll allow configuring that.

As for the video file length issues I'll test and have fixed for the next release!

[gguillemas]

That's great to hear, I appreciate your answer! Let me know if you need me to do any further testing.

I'll take this chance to commend you on the great work you are doing on this project. I personally really like your approach to working on the development as well as the decisions and changes you have made so far 😄

On a slightly related note, I have noticed that WebM video files (video/webm), also commonly downloaded from Youtube, fail to generate a preview as well. Looking at the code, this may be just a consequence of not being included in this list. Perhaps this omission is deliberate due to some incompatibility to generate previews. Otherwise, would you like me to open a separate feature request to support previews for WebM video files?

[gtsteffaniak]

Awesome, appreciate it! I'll make debugging ffmpeg/video integration easier in 0.7.5 for future issues and have this fixed.

plan to release on Monday.