As of version Plex Media server 1.9.3.4290, the script below is no longer required and Plex Hardware Transcoding works out-of-the-box.
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Please keep in mind that HW Transcoding with Plex Media Server ("PMS") is still in an experimental stage and requires a Plex Pass.
I did manage to do get HW Transcoding working on my new Synology DS216+II by doing to following. The first solution is the "safe" solution and requires no knowledge of SSH at all. The second solution requires some knowledge of SSH, and this solution will be implemented by Plex in the next release
Solution 1 (no SSH knowledge required)
1. Stop your current PMS
2. Download the PlexMediaServer build 1.8.1.4140 - Hardware Transcoding Preview 4 for Synogly from this link
https://downloads.plex.tv/plex-media-server/1.8.1.4140-82ea538ca/PlexMediaServer-1.8.1.4140-82ea538ca-x86_64.spk
3. Install downloaded PMS. If you current PMS is higher than 1.8.1 you need to remove your current PMS installation first.
4. Start the new installed PMS
5. Start Plex and goto Server -> Transcode and turn on the hardware acceleration option.
6. Go to Control Panel -> Task Scheduler
7. Create -> Triggered Task -> User-defined script
8. In General, Task: "Allow transcoder hardware access", User: root, Event: Boot-up, Check Enabled
9. In Task settings, run command:
if [ -d /dev/dri ]; then
chgrp video /dev/dri -R
chmod 755 /dev/dri
chmod 666 /dev/dri/*
fi
10 . Restart PMS and HW Transcoding should be enabled on your Synology DS216+II
Solution 2 (requires SSH knowledge)
1. Stop your current PMS
2. Download the PlexMediaServer build 1.8.1.4140 - Hardware Transcoding Preview 4 for Synogly from this link
https://downloads.plex.tv/plex-media-server/1.8.1.4140-82ea538ca/PlexMediaServer-1.8.1.4140-82ea538ca-x86_64.spk
3. Install downloaded PMS. If you current PMS is higher than 1.8.1 you need to remove your current PMS installation first.
4. Start the new installed PMS
5. Start Plex and goto Server -> Transcode and turn on the hardware acceleration option.
6. Open an SSH terminal session and modify the following file
file: /lib/udev/rules.d/60-fix-plex-hw-transcoding.rules
Currently: SUBSYSTEM=="dvb", GROUP="video"
Replace with: SUBSYSTEM=="drm", GROUP="video", MODE="0660"
7.Restart PMS and HW Transcoding should be enabled on your Synology DS216+II
Plex is investigating a solution to make the PMS with hardware decoding working out-of-the-box on a Synology NAS. The issue is caused on how Synology configured the access the transcoder device on the NAS. Solution 2 will be implemented in the next PMS release with hardware transcoding.
More info:
https://forums.plex.tv/discussion/282794/hardware-transcoding-preview-issues-platform-synology
Edit August 11th, 2017: Changed the script as advised by Plex. Thanks to @ChuckPA from Plex for all his efforts.
Edit August 24th 2017: Configure script via Task Scheduler, so no ssh is required. Thanks to @mhofman for the tip.
Edit August 24th 2017: Created 2 solutions (one with, and one without SSH knowledge).
Edit October 3rd 2017: Script 2 has been implemented in PMS version 1.9.3.4290 and higher.