Playback failed due to a fatal player error. (transcoding)

[Jorduino]

Jellyfin version: 10.9.9.
Installation method: docker (compose, linuxserver.io) https://pastebin.com/uc1d1CD6
FFmpeg log: https://pastebin.com/qUpBzeuW
Jellyfin log: https://pastebin.com/SpBPKp1u

I tried to enable hardware acceleration, installed the nvidia-container-toolkit, appropriate drivers, etc, but whenever hardware acceleration is enabled in jellyfin it only gives the "Playback failed due to a fatal player error". I looked through the forum and tried pruning the docker and reinstalling but no luck. I tried 

Code:

docker exec -it --user abc jellyfin bash

and ran 

Code:

ffmpeg

and it said command not found, but 

Code:

/usr/lib/jellyfin-ffmpeg/ffmpeg

seems to return version info etc, so i think it is installed correctly. the logs say something about the codec not being supported but in the jellyfin settings i have tried with all codecs enabled or disabled and getting the fatal player error either way.