Very high cpu load on certain files

[hypapaya]

Hi,
I am relatively new to jellyfin and have a small library by now. Most videos (mp4 and .mkv) load very fast and use about 2% of my CPU when being played. However, there are two .mkv files in particular. that when being played, need a while to load in properly (at first it stutters, and I can’t skip to a different time stamp). When asking a friend and ChatGPT they both told me that it could be a weird codec that need ffmpeg to be concerted live. Task Manager shows that ffmpeg command line uses al the CPU. Are there any commands in ffmpeg that can like reencode the video to make it jellyfin native? Tried some but none worked. Either the new video lagged like the old one or ffmpeg spat out an error that it doesn’t understand the command. If any of you guys have an solution that would be really nice. If there is anything that you need to know feel free to ask.    

[flymetothemoon]

The file is "AV1" and maybe you don't have transcoding enabled? And maybe your hardware doesn't really support "AV1"?
What cpu and gpu or gpus do you have?

[hypapaya]

I currently am running jellyfin on my laptop. I have RTX 4060 Laptop for the hardware acceleration and have an Ryzen 7 7840HS if I am not mistaken and have it enabled for av1. I looked it up and my cpu an gpu should fully support av1. I forgot to mention it originally but the file has a lot of subtitles and like 6 audio tracks integrated. Could that be part of the problem?

[flymetothemoon]

Usually it happens when it's trying to software decode/encode instead of hardware. Maybe something in these options on your server needs to be changed? Or some playback settings on your client? Otherwise I don't know