Hello,
Recently i bought Synology DS918+ and plex pass so i can enable Hardware acceleration in transcoder settings.
Problem is when i try to transcode HEVC 4k to 8bit 1080p it is very slow at transcending and cpu is at 99%. I have try some HEVC 1080p to 8bit 1080p transcoding and it is still very slow with constant buffering.
I think HEVC transcode is not working when HA is enabled,i was planing to buy lifetime plexpass but now i see this is not working on hi-end NAS like this :-/. Can someone please confirm if this is true or there is a solution for this problem?
Thanks.
Your DS918+ isn’t a “high end” unit. It’s a Celeron-based NAS. It’s not a ‘Core’ class CPU. A QNAP TVS-1282 is a high-end NAS.
If it had a SkyLake or KabyLake, that would be high-end.
They are doing false advertising of their products. It says on their site i and qoute “Also capable of transcoding up to two channels of H.265/H.264 4K videos at the same time”.
I have download their ■■■■■■ DS video, i can’t play HEVC 4k video with that app. What am i missing here? Is there a way to transcode 4k hevc ?
I am sadly in the same boat. All my other content plays just fine off the Plex server on the DS918+, but 4K movies misbehave. I get video fine, but no audio. 
Anyone have any suggestions on resolution? Or is this just a no-go?
Me again. I found via another thread a comment about hardware acceleration, and realized that wasn’t showing up for me. Re-downloaded Plex from the Plex site as a Plex Pass user, and found that now hardware acceleration is available. Yay! Not only that, but now 4K is working just great off the DS918+. Note that I did add another 4GB of RAM to it (for a total of 8) before I was testing 4K playback, so if you’re rocking just the pre-installed 4GB your mileage may vary. Either way, this is awesome news. 
Yay!
4K movies, specifically HEVC, depending on bit depth (SDR or HDR) can be problematic.
Without knowing the specifics (XML) of a problematic movie, and the client being played to, I cannot be more definitive
Regarding audio failure, I will need to see the logs. it sounds like a codec download failure
Yes, 8GB of RAM does seem to be the sweet spot (Maxed out) in Synology
