Display manager freezes when mpv is open

mpv Information

mpv v0.40.0-dirty Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
 built on May 21 2025 20:53:16
libplacebo version: v7.351.0
FFmpeg version: n7.1.1
FFmpeg library versions:
   libavcodec      61.19.101
   libavdevice     61.3.100
   libavfilter     10.4.100
   libavformat     61.7.100
   libavutil       59.39.100
   libswresample   5.3.100
   libswscale      8.3.100

Other Information

- Linux version: NAME="EndeavourOS"
- Kernel Version: Linux P50 6.14.9-arch1-1
- GPU Model: Nvidia Quadro P2000
- Mesa/GPU Driver Version: OpenGL version string: 4.6 (Compatibility Profile) Mesa 25.1.1-arch1.2
- Window Manager and Version: i3 version 4.24 
- Source of mpv: arch repo
- Latest known working version: 0.39
- Issue started after the following happened: Installed version 0.4

Reproduction Steps

I did a system upgrade about 2 months and noticed that my computer started freezing for about 2 seconds every now and then. By freezing, I mean the mouse would hang and the window manager would freeze.

I had no idea what was causing it. I thought it was the Nvidia drivers since I only observe the freezing when my laptop is connected to an external monitor that uses the Nvidia GPU. I tried everything and couldn't solve the problem.

I figured out the problem by luck; the sort of thing you will never guess to be the problem. If mpv is open, and not even playing a video, the problem manifests when I am connected to an external monitor. Closing mpv fixes the problem completely. I installed an old version of mpv (0.39) manually and there was no issue anymore.

I recently did a full upgrade. The problem has returned with the latest version of mpv. I tried installing the old version, but now it seems that I can no longer do so as I start getting dependency issues like "libplacebo.so=349-64" being too new.

Expected Behavior

The computer should not freeze when I have mpv open.

Actual Behavior

The computer begins to freeze when I have mpv open. I get the message below.

Audio device underrun detected.

Audio/Video desynchronisation detected! Possible reasons include too slow
hardware, temporary CPU spikes, broken drivers, and broken files. Audio
position will not match to the video (see A-V status field).
Consider trying `--profile=fast` and/or `--hwdec=auto` as they may help.

Log File

output.txt

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested with the latest mpv version to validate that the issue is not already fixed.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

Start by reviewing the attached output.txt and reproducing the freeze with mpv open, an external Nvidia-driven monitor, and the reported system versions. Compare behavior with mpv 0.39 and 0.40, then trace the log around the audio underrun and desynchronisation messages. Done means identifying and fixing the regression without freezing the window manager or producing the reported underrun.