Already when playing 1080p60 videos (h264) I'm getting this problem sometimes. It may have something to do with scaling, because when I use a zoom level of 1:4 or 1:2 I never get the issue but already when using fit to window (65%), 1:1 or 2:1 I'm getting major A/V desync. When opening a 1920x1080 video the zoom level is 69% but if I change it to fit to window, which is 65% I'm getting desync again. I've tried with and without hw acceleration enabled (nvdec). I'm not maxing my hardware, I've got plenty of CPU, dGPU, iGPU left.
Usage:
CPU: 15%
iGPU (Render/3D): 35%
dGPU (if used): ~5%
I can play 4k60 h264 videos fine with smplayer/mpv.
Linux Mint 22.3
Avidemux-x86_64_20261018_legacy.AppImage, Avidemux-x86_64_20260516_legacy.AppImage, ...
Intel/nVidia Optimus
1920x1080 display