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Poor plex transcoding performance

Go to solution Solved by premikkoci,


Getting some 4k content, and noticing that when set to 1080p high, it has to stop and buffer contantly.

Task manager indicates ~60-80% cpu usage.

HW transcoding is enabled in plex.


- i3 9100
- asrock rack c246 wsi
- 6.2.3 U3 w/ Jun's 1.4b - DS918+ and driver extension

Plex seems to indicate transcoding is taking place on hardware

and cd/dev/dri ls indicates card0 + renderD128 present in the folder

Turning off hw acceleration + transcoding in plex yields no change in performance or CPU usage.

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Probably caused by HDR tone mapping. Native PMS on Synology does not have necessary drivers to do HDR tone mapping using GPU and so video transcoding is done by GPU and tone mapping by CPU. To utilize GPU for both video transcoding and HDR tone mapping, You need to use docker linuxserver.io PMS version which have all drivers.


So first try to turn off hdr tonemapping in PMS settings to make sure that the problem still occurs.

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