SOLVED: Slow Transcoding Playback Start

[wallythander]

Basic Rundown:

• Jellyfin 10.9.10
  
• In a hand rolled Debian bookworm LXC container on Proxmox, using Intel QuickSync for hardware acceleration. 
  
• In a ThinkStation P330 with an i7 8700t.
  
• Recently, any video file that requires transcoding takes several minutes to actually start playback.
  
• I would expect Jellyfin to begin playback in a couple of seconds at most. Direct playback works as expected. Anything requiring transcoding does not.
  
• The Web UI player on Firefox and Android.  The native player in the Jellyfin Android app. 
  

I have tried a couple of things, including updating Jellyfin, so I had this problem on an older version (I honestly can't remember which, but I try to stay relatively up to date). 

I have also noticed that FFmpeg creates a task successfully that I can see in intel_gpu_top, but that task does not use resources until playback begins, a couple of minutes after clicking play. 

Looking at the logs, I cannot see anything obvious.

The delay is long enough that I can't really use the integrated native player in the Android Jellyfin app.  It times out before transcoding actually begins.  Though, I did get it to connect once, and transcoding performance seemed unusually slow (below the framerate of the media itself) in the web player, it seems fine. 

I am playing back hand ripped and H265 encoded video files from Blu-Ray and 4K-UHD discs. 

Let me know if there is anything I didn't include, this has me stumped. 

Logs:
FFmpeg transcode log 2024-08-31_23-51-02.txt
FFmpeg transcode log 2024-08-31_23-32-55_92.txt
jellyfin-log20240831.txt
jellyfin-log20240901.txt

[TheDreadPirate]

Do you have any VPNs running? Are you using a reverse proxy?

And what changed between the 23-32 ffmpeg log and 23-51 ffmpeg log? AFAICT, the ffmpeg command is the same but the 23-32 failed for some reason? Did you setup the GuC/HuC firmware in between those logs or something for low power encoding?

[wallythander]

No VPNs running, this is all local, and no reverse proxy.

I think for the shorter one, I stopped waiting. But other than that, I didn't change settings. I can try to pull other logs if you think that would help, I am happy to try any troubleshooting steps.

I believe I set GuC/HuC up when I set up Jellfyin in an LXC on my own (rather than using tteck's script) in April/May, and haven't touched it since.

Do you think having the low power encoding options enabled might cause this? I don't believe I have changed those since I set this up.

What confuses me the most, is watching intel_gpu_top, I can see the FFmpeg process get created when I click play. It just sits and uses no resources for several minutes, then starts consuming resources when the video file starts playing.

[TheDreadPirate]

No. Low power encoding either works or it doesn't. Looks like it is working currently.

Is your storage local? NAS? Cloud storage?

[wallythander]

Videos are on a NAS, though my transcodes directory is local.

The computer that runs Proxmox has a 2.5gb ethernet connection to my network, and my NAS has a 10gb connection.

[TheDreadPirate]

For the lulz, can you create a small test library in the LXC running jellyfin, put one movie in there, what happens when you try to watch that movie?

[wallythander]

The Fast and the Furious, which is what my logs are from, is in a small test library with only 2 items in it, that I created when I first setup Jellyfin to test hardware transcoding. Though I first noticed it in a library with ~40 movies in it.

Is there anything I can do to help troubleshoot a bit better?

[TheDreadPirate]

The point of the test is to have the movies be local to the LXC instead of on your NAS.

[wallythander]

I see, that makes sense. It seems to work a lot better locally. Using RSync to monitor progress, I got surprisingly slow transfer speeds.

How much of a video file does Jellyfin need to have before it starts transcoding (out of curiosity)?

I am not sure why my network connection seems to be slow. At least it gives me a direction to try to troubleshoot, which is a relief.

Looks like iperf3 speeds are ~100mbps, which is slower than I would expect, but in Rsync I was only getting 8-10mbps. Strange.

I tried copying the same file over the same SMB share onto another computer, using the same 2.5gbe USB NIC, and it worked at ~200 megabits per second. iperf also seems to be notably faster.

[wallythander]

I figured I would try something other than SMB to see if that could be the culprit. Looks like that is the issue. NFS is a fair bit quicker. And switching to NFS makes the wait time before a video requiring transcoding actually starts playing a fair bit shorter. Not sure what suddenly changed to make performance over SMB quite so slow.

Going to mark this as resolved, since this is an SMB issue, and not Jellfyin related.