NVENC/DEC Hardware Initilization Issues

[DoctorZeus 0]

Howdy,

I have had issues with this one for a while now and have been pretty stumped on how to solve it.

I keep getting multiple errors when emby tries to initialize hardware encoding/decoding and is subsequently not available because of this.

Using Arch Linux and I have checked with the systemd service file to confirm that it also adds the emby user to the "video" and "render" groups so it should have access.

I can also confirm that I can transcode outside of emby no problem using my graphics hardware.

I have attached my hardware detection logs, if anyone has any ideas that would be greatly appreciated!

Many Thanks

embyserver.txt

hardware_detection-63751813816.txt

Edited March 20, 2021 by DoctorZeus
Added Emby Server Logs As Well

[Luke 40073]

Hi there, please attach the emby server log as well. thanks.

[DoctorZeus 0]

7 minutes ago, Luke said:

Hi there, please attach the emby server log as well. thanks.

Thanks for the reply, I have attached to original post.

[softworkz 4568]

@DoctorZeus - Did you install the latest Nvidia drivers, following the instruction on the Nvidia website?

[softworkz 4568]

To rule out any permission issues, you could go to the Emby installation bin folder and run something like 

sudo ./emby-ffdetect -hide_banner -show_program_version -loglevel 48 -show_error -show_log 40 nvencdec -print_format json

 

[DoctorZeus 0]

On 3/21/2021 at 2:48 PM, softworkz said:

To rule out any permission issues, you could go to the Emby installation bin folder and run something like 

sudo ./emby-ffdetect -hide_banner -show_program_version -loglevel 48 -show_error -show_log 40 nvencdec -print_format json

 

Please find attached and yes all NVIDIA drivers installed via the official arch repos.
Many Thanks!

embydetectout.txt

[softworkz 4568]

Thanks. The detection run via sudo has successfully detected the Nvidia GPU, while it failed when run by Emby.

I don't know  arch Linux, so I can't tell exactly what's wrong, but it very much looks like a permissions problem.

[softworkz 4568]

You can try to run without sudo and by impersonating the Emby user.

[DoctorZeus 0]

Thanks, what I thought as well.
It's actually setup and installed by the official package on the repos so I will see if I can report as a community bug after doing a bit of tweaking myself..

Edited March 22, 2021 by DoctorZeus
Quoted wrong response

[softworkz 4568]

3 minutes ago, DoctorZeus said:

Thanks, what I thought as well.
It's actually setup and installed by the official package on the repos so I will see if I can report as a community bug after doing a bit of tweaking myself..

What were your results without sudo and when impersonating the Emby user?
No need to post the results - just let me know what worked and what didn't..

Edited March 22, 2021 by softworkz

[DoctorZeus 0]

6 minutes ago, softworkz said:

What were your results without sudo and when impersonating the Emby user?
No need to post the results - just let me know what worked and what didn't..

The "emby-server" daemon is actually granted permissions to the "render" and "video" groups on runtime using the "SupplementaryGroups" flag in the service file.

Having said that actually sudoing into a shell for the emby user and running "ffdetect-emby" seems to initialize nvenc fine..

[DoctorZeus 0]

There is also the emby-server service files here:

https://github.com/archlinux/svntogit-community/tree/packages/emby-server/trunk

 

[softworkz 4568]

3 minutes ago, DoctorZeus said:

The "emby-server" daemon is actually granted permissions to the "render" and "video" groups on runtime using the "SupplementaryGroups" flag in the service file.

Having said that actually sudoing into a shell for the emby user and running "ffdetect-emby" seems to initialize nvenc fine..

Inside the shell for the emby user, did you run with sudo or without?

[DoctorZeus 0]

9 minutes ago, softworkz said:

Inside the shell for the emby user, did you run with sudo or without?

Sudoed into a shell for the emby user, didn't give it any additional permissions or do any additional sudoing inside of that.

[DoctorZeus 0]

Ok I solved it.

The service has the argument "ReadWritePaths=-/dev/dri" seems to be the root cause, and removing it seems to restore transcoding.

Will query to the authors why that is.

Many thanks for your help though, beyond the call!

Edited March 22, 2021 by DoctorZeus

[softworkz 4568]

23 minutes ago, DoctorZeus said:

Will query to the authors why that is but its possible its a typo.

Already did that. 

Thanks a lot for reporting!

[DoctorZeus 0]

1 minute ago, softworkz said:

Already did that. 

Thanks a lot for reporting!

Also reported here:

https://bugs.archlinux.org/task/70123?project=5&string=emby-server

[alucryd 240]

8 hours ago, DoctorZeus said:

The service has the argument "ReadWritePaths=-/dev/dri" where the " - " is actually taking the permissions away..

It does not: https://www.freedesktop.org/software/systemd/man/systemd.exec.html

Where did you get that information?

[DoctorZeus 0]

1 hour ago, alucryd said:

It does not: https://www.freedesktop.org/software/systemd/man/systemd.exec.html

Where did you get that information?

I meant indirectly but yes in hindsight could have been clearer.

I was thinking originally of another service that uses the " - " to remove the permission but yes your right the " - " actually just specifies to ignore if it doesn't exist..

Frankly that just adds more mystery to the problem though of why this causes this..

Edited March 22, 2021 by DoctorZeus

[alucryd 240]

Does  the issue come up only on boot, or even if you restart it manually afterwards? Could be that your graphics device hasn't been fully initialized when emby starts. I know nvidia devices are troublesome for foldingathome for example, they initialize CUDA on demand, so when foldingathome first starts, they aren't available yet. Maybe something similar is happening here.

[DoctorZeus 0]

10 hours ago, alucryd said:

Does  the issue come up only on boot, or even if you restart it manually afterwards? Could be that your graphics device hasn't been fully initialized when emby starts. I know nvidia devices are troublesome for foldingathome for example, they initialize CUDA on demand, so when foldingathome first starts, they aren't available yet. Maybe something similar is happening here.

Sadly yes still occurs after restarting manually.

[alucryd 240]

I'm afraid I have no idea then:/ I ran this systemd service with an nvidia card for a couple years without issue, although I have now switched to amd. I never saw this issue mentioned before, there may be something specific to your particular system. You can override the directive permanently if you extend the systemd service, just create a file in /etc/systemd/system/emby-server.d/override.conf containing:

[Unit]
ReadWritePaths=/dev/dri

Then run systemctl daemon-reload and your fix won't be erased when you update the emby-server package.