I am running jellyfin in LAN on a Synology. I/O from harddisk shouldn’t be a problem being SSD on the same NAS. And WiFi should sustain a 4K stream. I have tried only web clients. How can I optimize the stream for such large file? Or how can I debug the bottleneck?
Are you transcoding? If so, need to make sure your CPU or GPU are up to he task.
How can I actually avoid the transcoding?
You can disable and tweak transcoding settings, but it might mean that certain media isnt going to be able to be played at all, if its a certain format. If you have a beefy computer, this shouldnt be an issue, but if not id check this out: https://jellyfin.org/docs/general/server/transcoding/
Depending on source file format and which client you’re using, it may be transcoding due to the client being unable to natively play the file.
If you don’t have the option of using hardware acceleration like Intel Quicksync, then the best option is trying to find a better client, or transcoding the source file manually before hand.
If your use 4K usually they are encoded as x265 so it will cause transcode when in browser.
would VLC better a better choice here?