[SOLVED] Transcoding uses 100% CPU, not so much iGPU

[oldskill]

First of all , thank you for the amazing work and support.

CPU: Core i5 6600 (HD530 iGPU)

Initially, I had installed Truenas, with their Jellifyn's container, had "GPU passthru" enabled and my CPU cores were near 0% while the iGPU was doing the transcoding.
For various reasons, I reinstalled and now have Ubuntu Server 24.04, with linuxserver.io's Jellyfin container (running on 100% same hardware where I had Truenas).

Got playback to work when I enable VA-API or QSV, but in both cases:
* all 4 CPU cores stay at 100% usage  (htop reports many /usr/lib/jellyfin-ffmpeg/ffmpeg processes consuming cpu)
* HD530: Render/3D is around 30% usage, Video around 50% usage (intel_gpu_top)
* not sure if this is related, but Playback fails when I enable Intel low-power consumption hardware encoding for h.264. I did not "Configure And Verify LP Mode On Linux", as Skylake is not listed there.

If possible, would like the HD530 to handle all the transcoding, to lower power consumption.
Like it was working on Truenas. I was probably testing with another transcoding type, though (cannot remember).

Everything below is with Intel Quicksync(QSV) selected for hardware acceleration.

Trying to transcode:
HEVC > H264
AAC LC > AAC

Jellyfin startup output: https://pastebin.com/UFma5Pui
Jellyfin logs: https://pastebin.com/pHcjRfCs
FFmpeg logs: https://pastebin.com/d0zUit2X
docker-compose.yaml: https://pastebin.com/2TC28REk  
Various shell commands: https://pastebin.com/qjyuxbZp

   

Sorry about the French in screenshot. Any help would be appreciated !

[TheDreadPirate]

Your audio is transcoding for this particular video. So that will always happen on the CPU.

If this is a fresh install, is the CPU usage may be from a library scan, chapter image extraction, or trickplay creation.

The log you shared is truncated so I don't have any information to confirm that. But your mention of "many ffmpeg processes" points towards some sort of library scan job.

[oldskill]

Ahh right the audio, forgot about that.

The CPU is only going to 4 cores 100% when playback starts, and stops when playback stops, so that did not seem related to some background task.

htop output attached. I was assuming that the -analyzeduration 200M was related to some analysis of the current media playback.

   

Just tested with another video, Direct Streaming H264, EAC3>AAC :
* HD 530 is fully idle , due to direct stream I suppose. It gets active if I reduce quality bitrate to 6 Mbps, to force video transcoding. Makes sense.
* 1 CPU core gets to 100% for about 1 minute. Then all cores go back to idling while playback continues, not sure why. But all this is CPU usage is audio encoding, like you said, I suppose.

I can upload full logs if you would like to see them. They just seemed huge, with mostly old errors which were fixed.

Otherwise, I'll just mark as solved !

[nyanmisaka]

6th gen intel / HD530 GPU doesn't support HEVC Main10 (10bit) which accounts for the high CPU usage.

[oldskill]

6th gen intel / HD530 GPU doesn't support HEVC Main10 (10bit) which accounts for the high CPU usage.

Ah right, I missed that too. Good catch !