Plex server on DS918+ - perfect hardware transcode of 4K 10bit HDR with low cpu usage



Plex server Version perfectly transcodes 4k 10bit HDR files with about 15% cpu usage :smile:

Thank you Plex team :smile:


Same here :wink: I’ve just migrate from 415+ to 918+ and it’s really more faster!
In all test I’ve made, always less than 25% CPU when transcoding.


Did you guys achieve this with a native install or a docker install?


Interesting, with the 718+ (Same CPU, less RAM) I'm not seeing quite the performance. Are you using an cache drive?


Native install here without cache drive.


Nice, good information.


Any Synology unit with 2GB of RAM should upgraded to 4GB minimum if used for PMS. 2GB is sufficient for NAS-only use but not when combined with other tasks.

DSM 6.1.4 requires 384 MB of memory to 'exist'.

PMS 1.10.x requires 256 MB of memory to 'exist' without transcoding.

Each frame of 4K video requires up to 32 MB of memory. 1 second of video requires up to 796 MB (3840 x 2160 x 4 (color)) + the overhead of the transcoder itself

This doesn't leave much room for buffers.

3rd party memory upgrade kits have been shown to be completely safe to use.

Kingston Hyper-X is 100% reliable in the DS1815+ This kit replaces both modules.
The DS1815+'s Atom CPU supports 16 GB of RAM. 8GB is more than sufficient . The as-shipped 2GB was grossly inadequate for PMS usage.


@ChuckPA said:
Any Synology unit with 2GB of RAM should upgraded to 4GB minimum if used for PMS. 2GB is sufficient for NAS-only use but not when combined with other tasks.

That's a good point/piece of discussion Chuck. I ordered a 16GB kit as I want to do a few other things with my NAS as well some day ( so that may help me realize the same performance as khr2011.


For comparison my usage converting 4kHDR HEVC files ( is 18-19% CPU usage but I am also transcoding Audio. My quality is set to 1080p20MBPS


Transcoding audio will always be a CPU task. It is not uncommon to see as much as 30% CPU utilization on a smaller processor such as the Atom C2538 to convert 5.1 -> 2 channel (web playback)


@electroach said:
Same here :wink: I’ve just migrate from 415+ to 918+ and it’s really more faster!
In all test I’ve made, always less than 25% CPU when transcoding.

I still run my ds411+ii which is so s l o w and thinking of upgrading to the 918+. Do these hibernate running plex server at all?


Drives do not hibernate. They will always run just as they always have. NAS grade drives are intended to run constantly. All HD's have a limited number of load-cycles (full head retract & powerdown -> power up & load). This is the critical wear point. It's better for the drive to be temperature stable than constantly heat cycling.


Thanks chuck. Currently running 4 HGST nas 4t drives. I’m at 91% capacity in the old nas.
So in your opinion, which has more power for plex services inc DVR (a nas would always be my storage)? Nvidia Shield pro or DS918+?


Given those two choices, I opt for the DS918+.

The specs are:

  1. You can put more RAM in the DS918+ should you need it. It's also X86_64 instruction set which allows you more flexibility.
  2. The DS918+ disk space is integrated and is more easily expandable.
  3. The DS918+ has built in QSV which is Plex supported.

The Shield is designed as a 'thick player' (something you can augment if you attach hard drives and run only their apps) which PMS was ported to for them. The DS918+ is a linux based server.


Ok, thank you for that info Chuck.


If you decide on the Synology, it's best if you have at least one completely fresh drive plus another (make free by shuffling around) so you can create the RAID volume (SHR).

Once created, you can begin transferring data onto the NAS one drive at a time. When complete, put that now-free drive into it and increase the RAID set (this does take time to add & expand the volume so be prepared).

You can also increase drive size over time but the process gets easier. In that case, shut down, pull one drive, insert the bigger drive, allow DSM to rebuild the volume on the bigger drive. It will help you through the process with Storage Manager.

A word of warning about Synology. They are pushing BTRFS filesystem. My recommendation is to not use it. Redhat has frozen their development efforts and has no intention of updating it on Redhat / Fedora systems.

Create the "Disk Group" first (the RAID set). Then create the volume (where your data is stored) with EXT4 formatting. EXT4 is tried and true. Although BTRFS is 20 years old, it isn't widely accepted due to its susceptibility to data loss/corruption. There have been reports of users needing Synology's assistance to recover their data on a BTRFS volume. While it can happen with EXT4, it's far less common.

All this will make sense when installing DSM or using their Live Demo. You can see Storage Manager and the menus.


I ve been running PMS on a Nvidia Shield pro for the last year. I just got a ds418play 1 week ago. I'm running PMS on both machines. I'm testing the crap out of them trying to decide if I switch everything over the NAS. The ds418play has the same hardware acceleration as the ds918+, but it's a dual cores celeron instead of quad core. I put a 4GB ram dimm so I have 6GB ram total.

The NAS has a lot of advantages over the Shield. The Sheild has few limitations :
*almost impossible to downgrade.
*update comes from the play store and often behind the current release
*you cannot backup and reinstall your database (unless rooted)
*you cannot install manually channels
*no access to plex install folder (unless rooted)
*cannot move pms data to adopted storage on the 16g version (unless rooted)

However, the transcoding capabilities of the Shield is amazing. I think it's superior to the NAS.

But don't get me wrong, I also impressed by the hardware transcoding capabilities of the NAS. I tried so far 3 transcoding stream 1080p x265 10bit with Dolby trueHD atmosX (without subtitles) and the NAS was doing the job. However, subtitle hurts. The NAS struggles a little bit on 1 transcode stream to my Nexus 6p 1080p x265 10bit with Dolby true HD and embedded srt subtitle. So I don't know why srt subtitles give a hard time to the NAS. I don't see this behavior on the Shield.

Also the Shield support hardware acceleration decoding of Mpeg2. For live tv, the Shield beats up the NAS.
However, on the Shield, playback is affected during tv recording. When the Shield is recording ota and I want to watch something like amazon video or any other playback at the same time, I see micro stutter on playback. That was annoying.

So right now I use the NAS for tv recording. Because the NAS struggles a little bit with subtitles and doesn't yet support Mpeg2 hardware decoding, I didn't yet switch totally over the NAS. But there is a lot more advantages to run pms on the NAS compare to the Shield.


Good info, thanks! You answered my question on the nas and dvr then.
@ChuckPA, I know that there is a migration procecedure on these Synology NAS devices according to synology. I was going to pull the drives (SHR/ext4) from the ds411+ii and move them to the 918+ and restore from a backup of the 411 to minimize work since everything actually works and is configured the way I want. I even have plex on there but disabled. Watching it trying to run plex is quite painful. Then, when with device is up and running, begin to increase the volume size.
On the shield, I’m not so keen on the plex exo player since I have a few mkv files that cannot be paused, restarted where one left off, nor FF which I have to use Kodi for. Would be nice if they ported PMP to work on the shield, but at least exo Plex Player has come a long way.


Subtitles are being worked on. It gets interesting with HEVC HDR due to that being the most complex part of the entire suite. Disc players do it with dedicated specially created silicon; software controlling a CPU/GPU takes a little longer to perfect all cases ;)


"PlexMediaServer-" Does this install hardware transcoding?

I am a 918+ user and a plex pass user but I do not have hardware transcoding.

I do not even know where to turn it on / off. I can not see the setting.