Converting WebVTT with X-TIMECODE-MAP

[doctorm]

I've run into this multiple times but never found a satisfactory answer.

A lot of VTT subtitles have tags like "WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:90000"

Every segment resets the time. Trying to convert it to a more useful format, like srt results in mistimed subs.

Subtitle Edit doesn't seem to properly handle it.
M3U8x is about the only program that seems to manage the timing correctly, but it is no longer being updated, and is janky and awkward to work with.

My last attempt failed to the point that I ripped with yt-dlp/aria2c. I then ripped a SECOND time with m3u8x.
Using Subtitle Edit, I loaded the yt-dlp version, and then imported the times from the m3u8x rip.

Yeah, not a great answer, but successful anyway.

I'm aware there is a patch to ffmpeg that is supposed to fix this, but I've never found it compiled into a release. (https://gist.github.com/SebiderSushi/bdf8d46d5501f7085d0b27d8a19eb12c)

Thoughts or idea?
Sample sub file attached.

[Nikse]

The "X-TIMESTAMP-MAP" should only occur once (on the second line) in a webvtt file.
See https://sdks.support.brightcove.com/features/synchronizing-webvtt-captions.html

[doctorm]

And when it isn't?

[Nikse]

Do you have a matching video file?

[doctorm]

Yes, but I'm not sure there is a proper way to provide that.

[Nikse]

Perhaps you could PM or email a link to a partial video file?
An fixed SRT file would also work I guess.

I would need some way to test, that the timestamps are correct.

[doctorm]

So a big thanks to Nikse who now has a Beta version of Subtitle Edit that addresses WebVTTs like this.
So for anyone else that runs into this you can start here: https://github.com/SubtitleEdit/subtitleedit/releases/download/3.6.7/SubtitleEditBeta.zip