reencoding to x264 introduces playback stutter in Chrome

[diviaki]

Summary of the bug:
Out of several videos one plays back with a weird jitter or stuttering in Chrome after I reencode it to x264. The original plays back normally.
Brave also affected, Safari, Firefox is not affected.
Happens in several ffmpeg versions across multiple platforms.

How to reproduce:

% ffmpeg -i source.mp4 -c:v libx264 re264.mp4
ffmpeg version N-68533-gcc774cd962-static arm64
built on 20240203

[diviaki]

The stutter intoduced propagated to a hls video converted from the bogus 264 video.

Other ffmpeg 264 encoders (h264_videotoolbox, libopenh264) does not suffer from this issue

[Balling]

I cannot see any obvious stutter. The issue is with what? Her talking?

[MasterQuestionable]

͏    Supposedly inconsistency between the output and source. (probably not apparently obvious)

[diviaki]

The issue is most noticeable on how the lips move so attaching a close-up screen recording on how Chrome on Macos plays back re263.mp4

[diviaki]

Might relate that in the original, 30 minutes long video the sound slowly gets out of sync finishing about 3 seconds earlier when video ends.

[MasterQuestionable]

͏    So it might mean the original has bad audio?
͏    No matter. Shouldn't be much relevant.
͏    (audio, video various streams can be each independent)

͏    At most it should mean the original was poorly produced. (therefore potentially broken)

͏    If such is the case, caution that FFmpeg currently may not handle non-perfectly-valid files in the most sensible way.
͏    E.g. ​https://trac.ffmpeg.org/ticket/11055