MPV seeks to beginning of chapter instead of seeking exactly 10 seconds

[eliardneru]

mpv Information

mpv v0.41.0-540-g9b3565c98 Copyright © 2000-2026 mpv/MPlayer/mplayer2 projects
 built on Apr 23 2026 16:10:28
libplacebo version: v7.362.0 (v7.360.0-16-g409c9a8-dirty)
FFmpeg version: N-124085-g162ad6148
FFmpeg library versions:
   libavcodec      62.30.100
   libavdevice     62.4.100
   libavfilter     11.17.100
   libavformat     62.13.102
   libavutil       60.30.100
   libswresample   6.4.100
   libswscale      9.7.100

Other Information

- Windows version: Windows [Version 10.0.19045.6216]
- GPU model, driver and version: GT 1030 (driver 32.0.15.8180 (NVIDIA 581.80) DCH / Win10 64, oct 29 2025)
- Source of mpv: Windows builds by zhongfly (2026-04-24 12:19)

Reproduction Steps

1. open a mkv file with chapters (I would not be able to describe what makes this video special, mediainfo output attached)
2. seek to either a bit before or a bit after a chapter start
3. if a bit after seek back, and vice versa

Expected Behavior

it seeks 10 seconds forward or backwards exactly

Actual Behavior

it seeks to the beginning of the chapter

Log File

output.txt

mediainfo.txt

Sample Files

none due to copyright issues

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

• I tested and confirmed that the issue exists with the latest release version or newer.
• 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.

[eliardneru]

created a sample file, it displays the same issue: https://www.mediafire.com/file/gs17mnjxtrn0hwp/sample3.mkv/file

[guidocella]

Works in ffplay. Likely an issue in mpv's mkv demuxer.

[kasper93]

Works in ffplay.

I see the same seeking behavior as in mpv. lavc cannot decode frames, and skips to next decodable frames, which is likely next keyframe.

Likely an issue in mpv's mkv demuxer.

What do you mean? There is no behavior difference with --demuxer=lavf

[guidocella]

Ok it's just harder to see in ffplay because it seeks by 10 seconds. The video is just broken then.