Question about GPU for HW Acceleration

Plex Media Server Desktops & Laptops
1

Greetings everyone!

I have been using Plex for a couple of years now. I have my server colo’ed at a Datacenter as I have 4K Content and my home connection isn’t good enough for this,

Until now, I have hosted the server on a Win10 Physical 7700K box with a Nvidia GT1030 GPU, used for HW acceleration. So far it has worked well but even with the 7700K I noticed a pretty big usage of the CPU.

Now, I have gotten my hands on 2x HP DL360 Gen9 servers with Dual Xeon E5-2620v4’s and would like to host the Plex server as a VM. So far I have managed to get the GPU passed directly through to my VM and the HW transcoding seem to work (shows (hw) in the transcoding info for a item being played).

Now, my issue is that the 2620v4’s doesn’t have that high of a clock (and also not quicksync). I looked a bit around and found a Nvidia Matrix for Decoding/Encoding content: https://developer.nvidia.com/video-encode-decode-gpu-support-matrix#Encoder

I have the GT 1030 and here, all of the boxes checks “NO”. Since all other cards checks “YES”, would it be ideal for me to get a GTX 1050? Would this put less strain on my CPU or would it not help at all?

Thank you all!
Chris

2

The go-to in the price range you are looking for is the p2000. Consumer grade gpus like the 10x0 have a maxiumum stream count of 2. so even if you have 10 transcodes the gpu will only help with 2 of them.

side note - if you are using VMWare vCenter you can add horizon view to it to create a gpu profile that allows you to not hard passthrough the GPU. This WOULD require having a GPU in all hosts, but allows for snapshots/vmotioning/ram-allocation

3

Hey and thanks for your answer! The limit of 2 transcodings is not a problem really, mostly it’s a direct stream but for when I or some of my family members use the phone, tablet or something else it’s just nice to not have the CPU go bonkers. :slight_smile:

The box is hosted on Proxmox, but I have a zentral zfs box which takes snapshot volume-wise.

4

I looked some more at the Quadro P2000 and won a new one on ebay for 300 bucks. It’s christmas time so it will arrive next week or so… then we’ll see how it works. :slight_smile:

5

I have installed the P2000 and HW transcoding seem to work but is there a reason why my CPU is being hammered as well? This is causing buffer :frowning:

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6

Is it running in a Windows VM or Linux?

On Linux the P2000 will only encode, the cpu will decode.

7

Hi,

I am running Windows 10 64 bit. Should be release 1809. Is there some log where I can check what the CPU is actually doing?

8

I don’t have a P2000 but others have posted difficulties getting it to do both decode and encode on Windows. It could be a driver problem or more likely that your are on 1809 release of Windows.

%LOCALAPPDATA%\Plex Media Server\Logs

You could also in a browser go to the https://app.plex.tv/web
Login and check your Status > Console and watch the logs as you try to play some media.

9

Note that audio transcodes are performed on the CPU, not the GPU. Dashboard / Status page referenced by @pl_5309 will show you if audio (or video) is transcoding.

If nobody is streaming or transcoding, then Plex could be generating preview / chapter thumbnails, which uses the PlexTranscoder process.

Logon to server via Plex Web and click on activity icon in upper right of window. Will provide some info on server activity.

10

Ok so I looked into the log file… this is what I get:

Dec 28, 2018 17:42:04.682 [10100] ERROR - QueryParser: Invalid field ‘onlyTransient’ found, ignoring.
Dec 28, 2018 17:42:11.713 [8008] ERROR - [FFMPEG] - Error initializing an MFX session: -3.
Dec 28, 2018 17:42:12.869 [8008] INFO - [FFMPEG] - MFT name: ‘Microsoft AAC Audio Encoder MFT’
Dec 28, 2018 17:42:13.573 [8008] INFO - [FFMPEG] - MFT name: ‘Microsoft AAC Audio Encoder MFT’
Dec 28, 2018 17:42:13.823 [7948] INFO - [FFMPEG] - MFT name: ‘Microsoft AAC Audio Encoder MFT’
Dec 28, 2018 17:42:14.354 [7948] INFO - [FFMPEG] - MFT name: ‘Microsoft AAC Audio Encoder MFT’
Dec 28, 2018 17:42:20.822 [8008] ERROR - [Transcoder] Could not write header for output file #0 (incorrect codec parameters ?): No such file or directory
Dec 28, 2018 17:42:20.822 [5716] ERROR - [Transcoder] Error initializing output stream 0:0 –

I also looked on the web panel, this is what it looks like:

image

Looks like the audio isn’t being transcoded hardware-wise… is this normal? hard for me to imagine that this would hammer the CPU that much.

11

In addition to the previous info, I can see that the GPU is (should be) both encoding and decoding…
image

I had a transcoding going and then stopped it… both went from 8-9% to 0%.

12

Audio transcoding is done on the CPU, given your stats you should handle 8 streams without too much trouble. Probably less than you were hoping for, the GPU can do more with more CPU.

13

Ok but is the audio transcoding really taking so much CPU power?

It would not be so ideal if I had to change my 2620v4’s because the clock is too low. :frowning:

14

I suspect you are getting hit with subtitle overhead, the CPU does the sync with the video. Do you have any media without subs that you can run through and measure?

15

What do you see for CPU utilization when there is no streaming? Is PlexTranscoder still running?

Also, play a video with AAC audio, which will direct play in FireFox. What Plex processes are running & how much CPU are they using?

16

Greetings!

I do not see any utilization on the CPU side at all (2-3%). There’s only some activity when the Plex server rescans the media for new content.

I tried to do without subtitles but this did not change anything in regards to usage. :frowning:

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