Plex Media Server Docker hogs CPU

Plex Media Server
4

Please verify your Plex Media Server version.

4.76.1 is the version of Plex Web.

Check the Plex Media Server version at Settings → Server_Name → General or your list of Authorized Devices.

You would see (hw) on the Plex Dashboard. Transcoding is a two step process: The video is decoded from the current format, then encoded to the desired format. Ideally, hardware acceleration is used for both steps.

Example: The first (hw) is for decoding the video, the second for encoding.
hw-accel

It is not always possible to direct play or direct stream subtitles. Sometimes they must be incorporated into the video stream, becoming part of the video frame. This is called “burning” subtitles.

Subtitle burning uses the CPU, even when hardware accelerated transcoding is in use. Due to the weak CPU in Synology NAS, this generally results in high CPU utilization. The end-user may also experience buffering if the CPU cannot burn the subtitles in real time.

Plex clients vary widely in their ability to handle subtitles. There is no master list of subtitle capabilities across Plex clients. However, in general:

  • Enabling SSA/ASS subtitles results in subtitle burning on almost any Plex client. The Plex desktop apps seem to handle SSA/ASS without requiring burning.
  • Enabling image subtitles, PGS & VOBSUB, on Plex SmartTV apps results in subtitle burning.
  • If the audio is transcoding, enabling any subtitle on Plex SmartTV apps results in subtitle burning.
  • The Plex Android & Android TV app will play PGS/VOBSUB/SRT subtitles w/o burning. SSA/ASS subtitles are still burned into the video.

Yes. Any user, whether local or remote, can cause subtitle burning by enabling subtitles that match the conditions mentioned above.

No.

Technically, you could disable video transcoding, but that is not feasible for most people. No transcoding means no subtitle burning. However, if the video needs to be transcoded due to bandwidth limits or other non-subtitle related reasons, Plex would simply refuse to play the video and the user will receive a (somewhat vague) error message, “the server is not strong enough to convert the video.”