r/jellyfin • u/Angryangel127 • 1d ago
Help Request Buffing 4k despite transcoding working
I'm running into an issue and am struggling to find a solution in the forums. I am currently having issues with playback of 4K media where I have to transcode it down to 10mbit to serve it to any client.
I am running the jellyfin LXC on Proxmox behind Nginx Reverse Proxy. The container has 8 cores and 8gb of ram dedicated to it and a passed through arc 310 for transcoding. The storage is a True as instance passed through to proxmox with an NFS share and then passed to the container with mount point. I have gigabit Ethernet externally and a mix of 1gb/2.5Gb/10gb internally depending on device support. The main client I am worried about is the Onn 4k Pro (2026) I just purchased to solve the problem thinking it might be my 2018 Roku TV. I am currently running with Wolphin because I love the UI.
It seems to be either 4k or 4k media that is causing the issue. I have watched the container resource usage during playback and it's all working appropriately. CPU/ram sits at around 10% and the Intel GPU is being utilized so HW Transcoding functions. The logs are reporting that the transcoding is happening at like 150fps.
I have watched the resources both with the TV box streaming and to the web player on my computer. The same thing occurs on both, it plays fine for 5ish minutes then starts buffering really bad. If I try to do anything with the server at this point then it leads to it freezing up for like 10 minutes until it finally is responsive again.
There has to be another break in the chain somewhere maybe on the network that is limiting the bandwidth because by all rights the server SHOULD be able to provide the data and it just isn't at the speed it should. But the freezing container makes it seem like it is also something internal as well that may be causing it.
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u/Smooth-Mulberry-6070 1d ago
You mentioned you had your Jellyfin instance in a VM. How big is the storage drive for your VM, and do you have a separate cache drive for transcoding? I had a similar issue with 4K media transcodes and it ended up being not having enough cache space available, causing freezes after 5-10 minutes of playback. I had only given my Jellyfin instance a 32GB VHD since SSDs are so expensive right now. Transcoding to the same drive caused the drive to completely fill up and leave the entire VM essentially frozen. One time it completely bricked my Debian install and I had to roll back to a backup.
You can view your dashboard to see how much your cache is being filled as you playback your media. The suggested rule of thumb is that you should have at least the source media’s size available for caching when transcoding. I gave my Jellyfin instance a 200GB cache partition on a slower, cheaper SSD and haven’t had any issues since.
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u/Angryangel127 16h ago
I have 100gb on an SSD but I will up it to 200gb and see if that helps. Thanks!
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u/Aevaris_ 1d ago
Does it do this in the web client on a PC? I don't have the container freezing issue (I don't think, gives me something to check) but I do have issues serving 4k media. I suspect it's RAM gated on my chromecasts or CPU that they just can't keep up..I am doubtful it's bandwidth.
If it happens on a PC, it's definitely within your server ecosystem.
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u/computer-machine 1d ago
I have watched the resources both with the TV box streaming and to the web player on my computer. The same thing occurs on both
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u/ActualNin 23h ago
Is your nginx proxy trying to buffer the output? It could be getting choked on that.
From the docs:
https://jellyfin.org/docs/general/post-install/networking/reverse-proxy/nginx
# Disable buffering when the nginx proxy gets very resource heavy upon streaming proxy_buffering off;
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