Jellyfin fatal player error

Plex has been a mainstay for serving up media at home but it seems to have changed lately towards a more and more commercial offering. A friend recommended Jellyfin and I deployed it on my Synology NAS in a Docker container.

I did a few quick tests in a web browser and everything looked good. But then my Jellyfin android app told me:

Playback failed due to a fatal player error

Everything looked fine in the browser, so it was time to dig in.

Checking the logs #

I opened up an ssh connection on the Synology to check the logs and found something unhelpful:

Jellyfin.Api.Helpers.TranscodingJobHelper: FFmpeg exited with code 1

Running a few searches led me down rabbit holes to plenty of GitHub issues. None of them fixed the issue.

Checking the browser again #

I went through a few different videos from the Synology and played each. They all looked fine in Firefox until I reached one that seemed to stutter. The frame rate looked as if at least half of the frames were bring dropped.

That particular video was in 4K with a high bit rate. Back on the synology, the CPU usage was through the roof.

I configured graphics acceleration when I deployed Jellyfin. Perhaps it wasn’t working?

Jellyfin deployment #

I deployed Jellyfin using the upstream guides with docker-compose:

jellyfin:
  image: docker.io/jellyfin/jellyfin:latest
  container_name: jellyfin
  user: 1026:100
  network_mode: "host"
  devices:
    - /dev/dri
  volumes:
    # removed
  restart: "unless-stopped"

One of the GitHub issues I stumbled upon suggested being specific about the video devices that are mounted inside the container.

$ ls -al /dev/dri
total 0
drwxr-xr-x  2 root root              80 Jun 10 20:23 .
drwxr-xr-x 12 root root           14140 Jun 10 20:24 ..
crw-------  1 root root        226,   0 Jun 10 20:24 card0
crw-rw----  1 root videodriver 226, 128 Jun 10 20:24 renderD128

I adjusted the deployment in docker-compose.yaml and tried again:

jellyfin:
  image: docker.io/jellyfin/jellyfin:latest
  container_name: jellyfin
  user: 1026:100
  network_mode: "host"
  devices:
    - /dev/dri/renderD128:/dev/dri/renderD128
    - /dev/dri/card0:/dev/dri/card0
  volumes:
    # removed
  restart: "unless-stopped"

I redeployed jellyfin:

$ docker-compose up -d jellyfin

The Android app still had the fatal player error.

Users and groups #

Most of my Synology containers use the uid/gid pair of 1026:100 so allow them to read and write to my storage volume. The /dev/dri/renderD128 is owned by the videodriver group:

$ grep videodriver /etc/group
videodriver::937:PlexMediaServer

This likely came from a time when I installed Plex on Synology via one of the Synology applications rather than from a container. (I’m not sure, but that’s my guess.)

I added that group to the container:

jellyfin:
  image: docker.io/jellyfin/jellyfin:latest
  container_name: jellyfin
  user: 1026:100
  network_mode: "host"
  group_add:
    - "937"
  devices:
    - /dev/dri/renderD128:/dev/dri/renderD128
    - /dev/dri/card0:/dev/dri/card0
  volumes:
    # removed
  restart: "unless-stopped"

After redeploying the container, the Android app worked just fine! Also, the video stuttering disappeared when viewing the 4K video from the browser. 🎉