SOLVED: Jellyfin hw transcoding not working

[canguy247]

Hey Folks,

I am hoping someone can help me with an issue as I am at the end of my knowledge here.

I have a server running NixOS and have a few containers running and all is well except for one thing.

The issue I have is that i want to use gpu acceleration for transcoding in Jellyfin and cannot for the life of me get it working.

Here is a summary of what I have done, with the logs/details below:
-confirmed Jellyfin running well without hardware transcoding
-installed NVidia drivers on host and container and passed devices through
-confirmed drivers working on host and container
-enabled NVENC hardware acceleration in Jellyfin - I get an error when playing media which uses the hardware
-ffmpeg log shows an error wrt no cuda device
-copying and pasting the exact ffmpeg command from the log into the container works fine
-changed the systemd service to run as root with no luck
-reached wit's end and came here

Details of what I have tried:
I have installed the drivers on the host and confirmed them as running with nvidia-smi:
NVIDIA-SMI 565.77 Driver Version: 565.77 CUDA Version: 12.7

I also did same in the container and confirmed them running as above.

The issue is that playing any media which requires gpu transcoding fails…ffmpeg log shows:
https://pastebin.com/V84W4i25


Here is the config for the container for reference:
https://pastebin.com/rWJKej8W

Checked ffmpeg sees the hardware:

Code:

/nix/store/n6jgkqjx03jalh683vxfv7mhl4xnhlc4-jellyfin-ffmpeg-7.0.2-5-bin/bin/ffmpeg -hide_banner -hwaccels
Hardware acceleration methods:
vdpau
cuda
vaapi
qsv
drm
opencl
vulkan

And then successfully used the jellyfin-ffmpeg within the container to do a conversion including using the full command from the ffmpeg log.

I do not know where to go from here...journalctl shows the following so it definitely can run ffmpeg successfully:

Code:

.
jellyfin[320]: [08:57:06] [INF] [1] MediaBrowser.MediaEncoding.Encoder.MediaEncoder: Available decoders: ["libdav1d", "av1", "av1_cuvid", "av1_qsv", "h264", "h264_qsv", "h264_cuvid", "hevc", "hevc_qsv", "hevc_cuvid", "mpeg2video", "mpeg2_qsv", "mpeg2_cuvid", "mpeg4", "mpeg4_cuvid", "msmpeg4", "vc1_qsv", "vc1_cuvid", "vp8", "libvpx", "vp8_cuvid", "vp8_qsv", "vp9", "libvpx-vp9", "vp9_cuvid", "vp9_qsv", "aac", "ac3", "ac4", "dca", "flac", "mp3", "truehd"]
.
.

Code:

.
MediaBrowser.MediaEncoding.Encoder.MediaEncoder: Available encoders: ["libsvtav1", "av1_nvenc", "av1_amf", "av1_vaapi", "libx264", "h264_amf", "h264_nvenc", "h264_qsv", "h264_v4l2m2m", "h264_vaapi", "libx265", "hevc_amf", "hevc_nvenc", "hevc_qsv", "hevc_vaapi", "mjpeg_qsv", "mjpeg_vaapi", "aac", "ac3", "alac", "dca", "flac", "libmp3lame", "libopus", "truehd", "libvorbis", "srt"]
.
.

Changed bind mounts to allowedDevices and all is good thanks to TheDreadPirate

Not sure why bind mounts are suggested in most NixOS docs I read or why I could still use hw transcoding from ffmpeg within the container. I am thinking the allowedDevices does something that is needed by the systemd.services sandboxing.