4K Playback horrible on Beefy Server

Plex Media Server Desktops & Laptops
1

Server Version#: 1.24.3.5033
Player Version#: Samsung TV App Client Version 5.24.1 Platform Version 5.5

So i just got done converting my old gaming PC into a Plex Server.

It is a pretty strong machine with:

9900KS @5.0 (at Turbo)
32GB of RAM
GeForce 1080Ti
Windows 10

The Media Source is a Synology NAS DS920+.
My TV is a Samsung QE65Q95T, basically 4K HDR.
I got the Plex Server on a dedicated machine with a fairly beefy CPU and GPU for transcoding just so i can watch 4K HDR.

However even with Hardware Transcoding on, i have like huge buffering issues, or so it seems.

The Dashboard will indicate that the movie is being hardware transcoded on original quality, but on the TV client side (and also browser client side on PC just for testing) the movie would play 10-20 seconds, stop and load for 10-20 seconds.

This is not something i would expect out of a machine like this, even if it was only the CPU transcoding, surely it can handle one 4K HDR stream?

I checked the network and its all connected up on 1Gbps on each end, so there should be no issue there.

I even tried to Map the NAS folders on the server using NFS protocol and add those as Libraries instead of the normally mapped SMB ones, but the issue is the same.

The funny part is? if i access the NAS directly from the TV instead of the Plex Client on the TV, and try to watch the same movie, it playbacks smoothly, no interruptions, in 4k HDR (it indicates it on the TV’s player on top left).

The ONLY reason i got a Plex Pass is to have auto subtitles from subtitles.org and the ability to watch it on a tablet in the future, but so far either im doing something wrong or i don’t know whats the deal. But i have invested into this Plex Server, moving it to an ITX case i had to buy with new SFX PSU i had to buy so i would like for it to work proper.

Am i missing something?

Appreciate all the help.

Best Regards,
Kobi

2

You can only get HDR playback with direct play. Do you have the player settings set to Maximum Quality?

Transcoding 4k HDR, even with HW, will require a high bitrate (since it attempts to retain quality going from HEVC to H264). This can be an issue on native TV apps and cause buffering/stuttering.

3

Hi man thanks for the feedback,

I remember from checking the Video stream quality it was indeed set to Maximum and said something like Original 30.8MBs or something like that.

Surely thats a bitrate a 1Gbps network can easily handle no? the TV plays the same content without issue, but only Plex lingers. Its actually worse then when i initially bought the DS920+ and told it to do the transcoding.

Im feeling like im doing something way off here just not sure what.

4

You will need to look in the logs to see why Plex is transcoding the movie. If I had to guess, the TV is reporting something back to the Plex client that is causing the movie to be transcoded. Most TV’s are not powerful enough to support high-bit rate HDR True Audio movies. Your better off using an external player that supports a variety of formats. The Nvidia Shield will play just about anything you can throw at it. That is what I use and I play very high bit-rate movies without any issues. I ended up getting the Shield because I too had issues with using Plex on my TV with 4K movies. It works fine for 1080p movies.

5

That though is my issue, even if the movie is being transcoded, should these specs not handle it easily? i mean a 9900ks and a 1080ti with hardware acceleration on should take on one 4k stream at the very least no?

And if true, how is it the Plex Client is unable to perform as well as the TV’s native video player? From what im getting the Plex Client is subpar to the TV’s player which also sits odd with me.

If i switch to a Shield, say a Shield Pro, can i use it as both Server and Client then, link to the NAS library locations and enjoy 4k HDR? no need for this whole specialized desktop headache?

Just trying to figure out which way to go, besides the money waste so far, at least i wanna go the right route. Shield Pro was gonna be my go to for server but i had the Mobo, Mem, GPU, and CPU laying around, so i went and invested in new PSU and Case and NVMe drive thinking ill just make a killer overkill plex server and not worry about playback issues, but so far 1 stream is really a disappointment.

Any ideas?

6

Your server is probably fine and not the issue. The built-in player is playing the file directly, while Plex apparently isn’t. If it was you might not have the issues.

If you look at the server logs after playing a video, look for lines that have “MDE” in them. They explain why a video was determined to need transcoding.

7

I find it easiest (because you get immediate feedback) to examine the Dashboard of the server via the web interface while playing. The panel that shows the movie being played and who is playing it will tell you quickly if and why it is being transcoded.

The Dashboard for the server is under the Activity menu with the icon that looks like a graph or heart beat at the top right of the screen on the web page. There is also a Plex Dashboard app for android with similar information.

8

So i saved the logs, but there are many text files in them, any specific text file i should look at? theres a lot of them. I opened some of them but now jumps up anything for MDE search.

Also, John thanks for the tip, i know of the Dashboard but did not think to share a screen from it, here is a snap of the dashboard while the movie is (poorly) attempting to play, playing 5 seconds buffering for 20.

36d8b6f5210ab208e0a7fe951334936e

9

The subtitles are probably causing your transcode. Do you get direct play if you disable them?

10

Issue is most likely the subs. When PGS subs are enabled they always cause buffer at 4k or even 1080p.

I have Plex running on TrueNAS Scale on this hardware:
Ryzen 5 5600x
64GB RAM
GTX 1080

Tried running and it’s always buffering. So I decided to install Plex on my PC (Windows) and put the movie on a NVMe disk (Samsung 980 PRO), to make sure it’s not disk.
PC Config:
Ryzen 9 5950x @ 4.625 GHz (all cores)
128GB RAM
RTX 3090

It’s a LITTLE BIT better, but still buffers so much that we can’t watch the movie. As soon as I change those subs to a SRT or disable them, everything is smooth.

11

That TV only has a 100mbps ethernet port, and the transcoding is making the video 141mpbs, so you can’t get the video to the TV fast enough which is causing the buffering.

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