Bad frame timing when playing 60FPS content on a 120Hz display

mpv Information

mpv v0.41.0-UNKNOWN Copyright © 2000-2026 mpv/MPlayer/mplayer2 projects
libplacebo version: v7.351.0
FFmpeg version: 8.0.1-3ubuntu1
FFmpeg library versions:
   libavcodec      62.11.100
   libavdevice     62.1.100
   libavfilter     11.4.100
   libavformat     62.3.100
   libavutil       60.8.100
   libswresample   6.1.100
   libswscale      9.1.100

Other Information

- Linux version: Ubuntu Resolute Raccoon (development branch)
- Kernel Version: Linux mamarley-laptop 6.19.0-061900-generic #202602081706 SMP PREEMPT_DYNAMIC Sun Feb  8 17:30:59 EST 2026 x86_64 x86_64 x86_64 GNU/Linux
- GPU Model: VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Phoenix1 [1002:15bf] (rev c4)
- Mesa/GPU Driver Version: Mesa 26.0.0-0ubuntu0~ppa0~26.04.0
- Window Manager and Version: kwin 6.5.91 (6.5.5 has the issue too)
- Source of mpv: https://launchpad.net/~mamarley/+archive/ubuntu/mpv-git (I own this PPA, so effectively a self-compiled binary.)
- Latest known working version: None
- Issue started after the following happened: I got a new 120Hz monitor

Reproduction Steps

I'm using the following configuration:

hwdec=auto
hwdec-codecs=all
profile=fast

When I play a 60FPS video on my 120Hz monitor, the video plays jerkily. mpv isn't reporting any dropped frames, however. If I switch the monitor's refresh rate to 60Hz, the video plays smoothly. The jerkiness seems to come and go; at some times it is considerably worse than others and sometimes it is nearly nonexistent. It seems like it might be a bit better with hwdec=vaapi, but not much, and I can also reproduce the issue when playing videos which cannot be hardware decoded on my system (mpeg2).

Expected Behavior

The video should play smoothly.

Actual Behavior

The video plays jerkily with apparent bad frame timing, as no dropped frames are reported.

Log File

I will attach the GPU log momentarily.

Sample Files

https://4kmedia.org/samsung-travel-with-my-pet-hdr-uhd-4k-demo/

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 reproducing the issue with mpv using the reported fast profile and hwdec settings, a 60 FPS video, and a 120 Hz display; compare it with 60 Hz playback. Review the attached GPU log when available and verify that playback is smooth at 120 Hz without reported dropped frames.