Plex Media Server Process Running around 90% CPU

Plex Media Server NAS & Devices
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Server Version#: 1.16.6.1592
Player Version#: Plex for Xbox One 2.38.0.70

I tried to watch a film yesterday and it would buffer every 5 minutes, I had a look on Synology to try and determine the issue.

I noticed that the CPU was very high (even after I stopped watching). It is the Plex Media Server Process and not the transcoding process. I have attached screenshots for reference and logs for reference. - could someone tell my why it is so high?

I think it may be an issue with the subtitles, I understand subtitle transcoding cannot be done via hardware so I downloaded some external srt files and can see the transcode is now hw. are the subtitles being added via the xbox or NAS?

Also what resources does audio transcoding use - how much CPU should I expect to transcode from DTS 5.1 to AAC?

ThanksPlex Media Server Logs_2019-09-09_09-20-03.zip (3.4 MB)

Screenshot%202019-09-09%20pro
Screenshot%202019-09-09%20pro974×513 150 KB
Screenshot%202019-09-09%20task
Screenshot%202019-09-09%20task973×514 150 KB

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You’re correct. Subtitles must (currently) be done by the CPU. Intel is working on an addition to the VA-API to support hardware subtitles but it will be some time before we see it.

Any Text-based subtitles, which the player can handle (most can), is fine unless the player is set for ALWAYS BURN.

Image based subtitles (PGS, VOBSUB, DVDRIP, etc) are images… These must be done by the CPU and require the most power. The J3455 doesn’t have the speed to do it.

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Thanks for the reply

Will the xbox process the subtitles even if the video is being transcoded?

This title has been problematic for me, the same CPU behaviour occurs when the title is Direct Streamed aswell.

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The Xbox is very very limited by Microsoft. While the dev can speak better to what it can and can’t do, if it’s asking for server involvement, I would trust it.

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If the subs are being burned in by the server would it show as Plex media server process or plex transcoding process?

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Yes. The DEBUG logs will also definitively show what is happening.

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Sorry which one are you referring to?
Is there a way you can tell from the attached logs in my first post?

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Yes, they do.

I do see the audio being converted (about 25% CPU load itself).

And the logs show ASS subtitles are being burned. Why this is happening is unknown to me.
This is where my knowledge is exceeded.

I do know ASS subtitles are a problem in the transcoder and being addressed in the new update.
Beyond this, I do not know.

Sep 09, 2019 09:04:48.889 [0x7f7f7dcd7700] DEBUG - Streaming Resource: Reached Decision id=395 codes=(General=1001,Direct play not available; Conversion OK. Direct Play=3000,App cannot direct play this item. Direct play is disabled. Transcode=1001,Direct play not available; Conversion OK.) media=(id=818 part=(id=818 decision=transcode container=mp4 protocol=dash streams=(Video=(id=2197 decision=transcode bitrate=39354 encoder=h264_vaapi width=1920 height=1080) Audio=(id=2198 decision=transcode bitrate=768 encoder=aac channels=6 rate=48000) Subtitle=(id=4501 decision=transcode bitrate=2147483647 encoder=ass languageCode=eng location=sidecar))))

 encoder=ass languageCode=eng location=sidecar)))
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Very helpful thank you.

The subtitle file is a .srt.
Is it transcoding the .srt to .ass?

Who would be the best person to ask as to why they are being burned?

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The SRT -> ASS conversion is because of the player.
I believe @Moussa is best to answer this.
With a bit of feed back from him, I can assist further.

11

After having a look around it seems that the subtitles will be burned in when some audio types are being transcoded to as seen here;

So I guess my best bet would be to wait until the Xbox One direct play buffering issues are fixed or to burn the subs into the film video itself.

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