Plex for Windows - 4k (offline) Playback is stuttering (really bad)!

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Server Version#: 1.31.2.6810-7000
Player Version#: 1.66.1.3632-4d9c7716

After lots of years with Kodi/VLC I’ve returned to Plex and went straight away all in with Plex Pass lifetime.

  • Setup the Plex Server on my Synology DS918+.
  • Setup the Plex Clients on all TV’s, Mobile Devices, PC, Notebook, Fire Sticks, Nvidia Shield Pro.

All pretty straight forward and a great experience so far, but…

  • 4K (SDR/HDR) movies and TVshows (mkv, x264, x265, HVEC…) with sizes up to 80GB per movie run fine on the Amazon Fire Stick on my smart TV. The Nvidia Shield Pro at my home cinema, even on my Ipad Mini 6 or Pixel Phone. Also my Gaming PC with high-end Hardware runs fine…obviously.
  • Every time actively selecting the highest/original 4K resolution! No render work to do by the NAS. All direct play/stream to the device.
  • Only my 2020 Lenovo Notebook with Intel i7 10th Gen + UHD iGPU is stuttering like hell!
  • The same movie runs instantly and smoothly with VLC player, streaming from the NAS via Wifi. No problem at all.
  • The stuttering is bad on battery power (high performance mode) and terrible on battery mode (balanced mode / not energy saver).
  • CPU load is at about 40% and GPU is close to 100% most of the time when a movie is running in Plex.
  • Direct Play and Direct Streaming is enabled.
  • I’ve messed with “Video Playback Quality” set to “low” and “low angle renderer”. Also with “hardware acceleration” which improved the stuttering a little.
  • Have downloaded the Movies within Plex for windows and played them in offline mode, just to make sure its not my WiFi.
  • The only way to force them to run smoothly is to select a lower resolution. The rendering of a lower resolution by the 918+ NAS is working really good and fast, by the way.

My main device for Plex is this Lenovo Notebook, which I intentionally specked with a 4K HDR OLED screen for the purpose of consuming movies on it.

Any Ideas or is Plex for Windows really that badly optimized?

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The content of this thread may be of help: New plex HTPC app, 4k video jerky/unwatchable

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Some steps further I can report that the videos are playable now, but still a bit jerky with regular framedrops below 24p.

I have added this to the mpf.conv, which basically gave me a smooth picture for 5 seconds and then it started to stutter again.

hdr-compute-peak=no
gpu-dumb-mode=yes

The second step was upgrading the Intel UHD graphics driver from the latest one supplied by Lenovo Vantage to the latest one provided by Intel Update Utility. This made quite a significant change. It is still nowhere near the smoothness of VLC, but at least “watchable”.

If there are any other command lines for the mpv.conf to reduce load / image processing, this info would be much appreciated. I prefer a steady framerate over a perfect picture if I don’t have to drop down from 4K/HDR altogether.

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MPV defaults to higher quality presets than VLC and you can fine-tune those with other directives. The low quality settings preset already sets the scaling to bilinear, turns off dither, as well as deband and hdr-compute-peak. You can see the whole list of directives here: mpv.io

Unfortunately the UHD graphics GPU really isn’t sufficient to do 4K/HDR properly but it sounds like your case is worse than others. I can play 24fps HDR content on a UHD Graphics 620 in an Intel NUC with just the preset and not having to set the gpu-dumb-mode. Though it drops frames with 60fps HDR content.

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