VLC's CPU usage 100% after graphics change (suspend-sleep, console switch, etc)

[onetruecliff]

Opening an instance of VLC to watch a video runs normally. However, if I pause the video and leave VLC open, then change the graphics (like putting the computer to suspend-sleep and then wake it up, or switching to a text-terminal ttys console), VLC's CPU usage jumps to 100% and stays there. I have to close the VLC instance and reopen it. The problem has been happening for at least a few months now. Wish I'd taken note of the precise time.

System Details:

Distributor ID: Ubuntu
Description: Ubuntu 20.04 LTS
Release: 20.04
Codename: focal
Linux Kernel: 5.4.0-37-generic #41-Ubuntu SMP x86_64
CPU: Core i5-3570K
Nvidia GTX 1060 (proprietary drivers, Nvidia-440)
KDE 5.18.5
X-Server: 1.20.8
Dual 4K Monitors over DisplayPort
Memory: 16GB

VLC version: 3.0.9.2-1 amd64

Any idea how to fix this problem? I've tried deleting my old 'vlcrc' and 'vlc-qt-interface.conf' files, then using fresh-default ones, but the problem still happens.

I don't know if this is a problem between the Nvidia drivers playing poorly with the x-server or kernel. I have been getting video-tearing for a while now intermittently. Just recently I forced a reinstall of nvidia-dkms-440 and that seemed to help. (Reinstalling triggered a recompile of the kernel modules which I assume was part of the problem because of recent kernel updates?)

[rom1v]

> if I pause the video and leave VLC open, then change the graphics (like putting the computer to suspend-sleep and then wake it up, or switching to a text-terminal ttys console)

I just tested suspending and switching to another tty, I could not reproduce the problem on VLC 3.0.10 (Debian sid, XFCE, X11).

> X-Server: 1.20.8

Doesn't KDE on Ubuntu use wayland by default?

[Rémi Denis-Courmont]

Hard to say. What's in the VLC logs? If there's nothing there, it's probably a driver bug, or rather unexpected corner case.

Generally speaking, you can't move video playback from one graphic device to another, as video codecs are stateful. You need to stop and restart anyway.