If your Synology NAS supports hardware transcoding and you need the group_add parameter to add it to the Docker Compose file for Jellyfin with hardware transcoding, I’ll show you in the guide below how to find this parameter so you can fully leverage hardware transcoding and avoid errors in the logs. Without the correct group_add parameter (usually the GID of the render or video group on Synology), Jellyfin cannot properly access the /dev/dri/* devices required for hardware transcoding. Below are three of the most common errors that appear in the logs:

Failed to open /dev/dri/renderD128: Permission denied
Failed to open /dev/dri/card0: Permission denied

[VAAPI] Failed to initialise VAAPI connection: -1 (unknown libva error)
Failed to create VAAPI device context

libva error: /usr/lib/jellyfin-ffmpeg/lib/dri/iHD_drv_video.so init failed
Failed to open the intel device

• STEP 1

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• STEP 2

🚀 CHECK IF YOUR NAS SUPPORTS HARDWARE TRANSCODING

• STEP 3

Go to Control Panel / Task Scheduler / Create / Scheduled Task / User-defined script. Follow the instructions in the image below.

• STEP 4

Once you click on User-defined script, a new window will open. Follow the instructions below:

1. 1. General: In the Task field type in “group_add“. Uncheck the “Enabled” option. Select root User.
   2. Schedule: Select Run on the following date then select “Do not repeat“.
   3. Task Settings: Check “Send run details by email“, add your email, then copy paste the code below in the Run command area. After that, click OK.

ls -nd /dev/dri/renderD128

• STEP 5

After you click OK on STEP 4, a new warning pop up window will open. Click OK.

After you click OK, type in your DSM Password then click Submit. Follow the instructions in the image below.

• STEP 6

After you click Submit at STEP 5, select your “group_add” Task, then click the “Run” tab. You will be asked to run group_add – click OK. Follow the instructions in the image below.

• STEP 7

Check your email. You should receive an email with the following output. The group_add number of your Synology NAS is the third number in the sequence. In my case, it’s 937.

⚠️Note: If you don’t receive an email, check to see if you have activated Email Notifications on your Synology NAS.