Plex transcoding ignores set buffer limit and occasionally resets

General Discussions
21

hmm, a couple thoughts.

first, I don’t think you have specified your hardware/os…

second, in the first full screenshot, you have ac3 5.1 (lossy) audio transcoding and subtitles transcoding

in the second full screenshot, you have a truehd (lossless hd) audio transcoding

you aren’t showing your other streams, are they transcoding or are they direct streaming (remuxing the same codec/resolution to a different container) ? direct streaming is less cpu

audio and subtitles are single threaded, so maybe cpu limiting factors at play.

of course none of that really explains why one particular client transcoding blocks others or exceeds the buffer so dramatically.

22

Ah you’re right, let me list hardware:

  • i5-7500 (Passmark of ~8K)
  • 24GB DDR4 RAM
  • 1050 Ti GPU
  • 4 x 4TB WD RED NAS

That should be the relevant stuff. As for the screenshots, the first one in this thread is the only one that had someone else streaming at the time of the screenshot, the other ones it was only just that 1 user streaming (these are times I don’t care about him using a lot of the CPU but they were when I saw him watching), I’ll have to keep in mind to grab a screen when there is at least another user, even if its just me for the sake of multiple.

I’m going to say a high majority of the content watched on my Plex ends up being transcoded - I don’t have any hard numbers atm, but every time I look, I see its being transcoded.

23

I can’t remember if this setting is plex pass specific, but check and see if it is there and it is set appropriately;

Plex > settings > remote access

Internet upload speed xxx Mbps

You can use speedtest.net to determine your internet upload capacity.
Enter an upload speed here and Plex can ensure it operates within this boundary.

Limit remote stream bitrate (mine set original no limit)

Set the maximum bitrate of a remote stream from this server. (this is the max any single stream can use)

additionally, the plex clients can control their remote stream quality, unfortunately the default is typically a low 4mbs 720 quality.

you can tell your users to set their remote quality to original or something higher that fits within your upload speed.

that might help alleviate unnecessary transcoding at the server side

24

Unfortunately that feature is Plex Pass, but I don’t think upload capacity is an issue (sorry, should have written that in the hardware specs as well!) I have symmetrical Gigabit, this is a screengrab from Fast.com, this is with some other network activity going on.

I’ll ask him to try setting it to a higher quality setting, not sure why he has it as low as it is with his internet speed able to support higher - we’ll see if there is any difference in behaviour.

Appreciate the tips greatly :slight_smile:

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25

he or they may not have thought to go looking for settings in the plex player client.

with plex pass, the server will take your total upload speed and essentially try to divide as many simultaneous streams up as needed to fit within the upload limit. (transcoding to various bitrates as needed)

since you have such great connection, your users should be using ‘original’ or max quality (assuming they have high enough speed download themselves, and that you don’t mind your users using a lot of upload bandwidth)

getting your users to direct play takes a big load off the server (no need to transcode), but obviously requires a really good upload speed.

26

How about asking this one user to reduce the size of his network buffer?
The relevant setting is accessible in the TV mode of PMP.
Tell him to not go over 128 MB

I assume he just cranked it up to the max of 512 MB one time and then forgot about it.

27

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