Just migrated to a new QNAP (TVS-951X) and there was an issue getting vaapi working in my emby docker container.
In QTS 4.3.6.0875 there are no default system groups (like video) and the /dev/dri folder is owned by admin:administrators with restrictive permissions, which are reset upon reboot.
It was necessary to create an autorun.sh script to set things up for docker use.
#!/bin/bash chown admin:video /dev/dri chmod 775 /dev/dri chown admin:video /dev/dri/* chmod 660 /dev/dri/*
The docker needs to run as a user assigned to the video group (or have the video group's GID listed in GIDLIST), run in privileged mode, and have /dev/dri passed through as a device.
This enables vaapi for me - qsv's a no-go.
Edit: Something like this is (probably only) needed when running the docker as a non-root user.
Edited by zeroidea, 18 March 2019 - 12:43 AM.