Buffering when transcoding

Server Version#: Version 1.41.7.9823
Player Version#: All

Good evening folks!

Currently trying to optimize my Plex settings to get the maximum performance out of it. I have some users who struggle with buffering so I am primarily trying to address that.

The setup is as follows:
Ubuntu 64-bit VM running on proxmox.
Proxmox has a Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz on the host, and the Plex VM has 1 socket and 20 cores given to it. The VM also has 32GB of RAM given to it, but it can easily get more if needed.

I also have an old GTX970 passed through to it, but I get that this thing probably doesn’t help at all being so old.

For network I am running 750/750mbit wired so that should be no issue.

When running files natively, 4K direct streaming both remote and local I have no issues what so ever. I get problems when trying to go from 4K → 1080p using transcoding.

Transcoder settings:
Transcoder quality: Auto
Transcoder temp directory: a tmpfs folder(RAM)
Transcoder default throttle buffer: 1200 (Randomly picked number)
x264 preset: very fast
HDR tone mapping enabled, as hable.
Hardware acceleration when available: enabled
Hardware-accelerated video encoding: Enabled
Transcoding device: Auto.

This is the output from Tautulli when I try to perform the same stream as one of my users:

Product
Plex Web
Player
Firefox
Quality
10 Mbps 1080p (9.4 Mbps)

Stream
Transcode (Speed: 1.2)
Container
Converting (MKV MP4)
Video
Transcode (HEVC 4k HLG -> H264 1080p SDR)
Audio
Transcode (English - EAC3 5.1 -> AAC Stereo)
Subtitle
Transcode (English - SRT ASS)
Location
LAN: 192.168.1.45
Bandwidth
9.9 Mbp

I know that the CPU is fairly old, but I would still expect it to handle this without any issues. Does anyone have any suggestions for where to start debugging?

Thank you very much!

Disable tone mapping and try again.
I would expect the CPU to be able to handle transcoding only without tone mapping.

You will need a newer GPU, I suppose.

To add to Otto,

  1. I have an E5-2690v4 . Don’t expect it to do any HEVC transcoding
  2. I have it paired with the Nvidia P2200.
    ( A popular internet retailer is selling this for $220 USD. Prices have dropped)

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