How to fix? Warning: Video is late by xxx ms

[JanMeki]

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

[eumagga0x2a]

Make sure you use an accelerated video display in Avidemux, i.e. NOT "Qt" / "RGB", preferably VDPAU (but with the graphics wired to Intel this might not work), OpenGL / QtGl or XVideo, else all the scaling work is done on the CPU. The best options are to use VDPAU hw decoder with VDPAU display or LibVA decoder with LibVA display (whatever works). If NVDEC is used, it always downloads decoded pictures to the main memory that need to be re-uploaded to the graphics card for display. This may still be beneficial, but not as efficient as it can be.

Another huge cause of lag can be the status bar itself, especially at 60 fps. Try hiding it via the "View" menü or restrict refresh rate of the GUI in Avidemux Preferences to a lower value e.g. by enabling the cap and setting the redraw interval to 20 ms (1000/20 = 50 fps) or higher.