4k playback buffering -- server hardware question with logs

[jps2041]

Server Version#: 1.14.0.5470
Player Version#: < latest version as of 12-15-2018 for fire-tv & browser-client >

I have been trying to figure out why my 4K content buffers on playback and I was hoping someone here could bring a fresh perspective.

Server hardware (HW acceleration enabled):
Intel i7-4930k @ 3.40GHz (6 core, 12 threads)
32GB DDR3 RAM
GeForce GTX 1050

I have tried to play several 4k movies with varying bitrates from 33KB/s to 56KB/s from several devices including a wired-LAN connected Fire-TV(v2) and a high powered 4k laptop also with sufficient network hardware.

The behavior is an occasional pause of 2-6sec to buffer and then it resumes – otherwise it starts relatively quickly and working normally.

I have observed the server CPU usage to be minimal and the GPU usage to spike to near 100% in the first split second of the video playing and then will linger between 8% - 34%, where spikes toward higher values occur when the GPU is transcoding to re-fill the buffer (I assume). Otherwise everything looks normal, and I confirmed that HW transcoding was enabled for both encode & decode using the server ‘now playing’ status page where it showed HEVC (hw) => H.264 (hw).

According to this page describing transcoding compatibility with NVIDIA cards, this one should be able to handle a 4k stream (especially when there is just the 1 stream).

Video Encode and Decode GPU Support Matrix

My CPU passmark’s around ~13k so I know it can’t handle a 4k transcode by itself, but should still be powerful enough to assist in any processing that may need to be done.

The attached logs were taken a few minutes after trying to stream a 4k movie while just the 1 stream existed. The (plex-web) client was a non-4k capable desktop with an i5-3570k and 16GB RAM
Plex Media Server Logs_2018-12-16_09-34-27.zip (7.1 MB)

Edit: For clarity, I know not all my clients can display 4k video, but transcoding to any 1080p format seems to suffer from the same buffer problem. Overall 2 of 3 clients tested have 4k-support, and 1 does not.

Can someone take a look at the logs and help me figure out where the bottleneck is?
I’d really appreciate it.

Thanks

[ccandbenterprise]

I am experiencing a very similar issue. Even in cases where it says “Direct play” and no transcoding. I get a similar buffer issue on 4k content. I know it’s not my hardware.

[tixetsal]

It’s not us. Plex is complete trash with 4K HEVC around 40 Mbps or higher. They don’t care though, because they already got out PlexPass money and are now trying to milk Jay-Z and add other functionality that no one cares about.