Recently i notice, on two of my servers, whenever i use auto adjust quality, there seems to be some ‘network performance issue’. The playback will start somewhat at 1080p or 720p, and more often than not, the client (iOS) will tell me my network is not able to provide a smooth playback and the quality will drop to 480p or SD. Or in the rest cases, the ‘buffering bar’ — the grey bar on the progress bar, is barely visible, meaning the Plex client is only buffering so slightly ahead of the playback.
However, when i manually select original quality (usually around 1080p 4mbsp to 1080p 12mbps), the buffering bar just flys. I can just forward/rewind without any problem, everything just loads instantly.
A lot times my Plex is struggling with auto ( 2-3mbps), but just flys with original (8+mbps), it makes no sense.
Once of my server is a dedicate NUC running only Plex (with sonarr+radarr), Ubuntu 18. It has a 8th gen i7 and i tried both CPU and GPU transcoding but no noticeable differences.
Another is a VPS with 2 vCPU, i got ~2-3x doing a offline transcoding. So I don’t think the server performance is a bottle neck.
Any advice how should i optimize my configuration? Or is there a option on iOS client to automatically select original quality when bandwidth is sufficient?
It’s likely that under original quality, the file does not need to be transcoded, so PMS can send the file as is to the client. When this happens, the client can build a significant buffer which can avoid buffering issues. When the file cannot be sent as is (i.e. PMS has to transcode the file), the media is then streamed as small chunks with each chunk being sent just in time before playback starts. There is no buffer on the client end for this. This is just the way streaming transcoded media works.
If you have multiple things playing at the same time, they are all fighting for bandwidth at the exact same time. You really can’t fix this except to limit the throughput for each stream so you leave some available for others at all time.
What I don’t understand is, if i can stream original quality @ ~8-10mbps and build up buffer quickly, i should be able to stream transcoded videos at at least the same bitrate, meaning i should be able to stream 1080p without problem right?
But with transcoding, i was only able to get 720p to SD @ below 3mbps, a lot of times at 0.9mbps.
I only have one client playing at a time, so neither raw transcoding performance and network bandwidth should be a bottleneck…
I see you mentioned, that if you play in original quality you have no issues but when you adjust the settings you get lag and buffering. Why not just leave it at original quality?
If you can provide your PMS and client logs after recreating this, we can better understand what is going on.
Another possibility is internet latency. If you can run a trace route between your server and client, that will show what the latency is. If it is high, that can really impact remote streaming.
I think there might be a bug or something else is wrong, i capped my remote streaming at 1080p 12mbps, and checked the ‘player smaller file’ option. So in theory those videos (which is most) should play directly instead of transcoding. However they are still being transcoded and streamed at 12mbps converted.
Unless i choose streaming quality at ‘maximum’ then it will start direct playback automatically.
I think it may be the latency issue, my two servers are in two different continents, and i’m Currently staying in the third…
Latency is around 150-250ms.
