Convert to/from SMTPE timing?

[darnn]

I never found myself needing to do this, but now that I have, I can't seem to find a way to actually do it:
I have a subtitle file that's in SMTPE timing. I need to convert it to, uh, whatever the normal form of timing is called.
That is, right now, when I view the subtitles with "SMTPE timing" checked in the Video menu, they appear at the right times. I want a file where they would appear at the same times but with "SMTPE timing" unchecked.
Specifically, I need to produce an ASS file to created burned in subtitles, but outside of Subtitle Edit, everything treats the ASS file as if it is non-SMTPE timing, and so doesn't display the subtitles at the right time.
Also, in Generate video with burned-in subtitles, there's no option to use SMTPE timing either, so I can't do it through there.

[niksedk]

Sync - Chang speed in percent has this:

[darnn]

This doesn't seem to work the same way as ticking SMPTE timing. For instance, in my ASS file, I have this line:
Dialogue: 0,1:22:28.88,1:22:30.38,Default,,0,0,0,,I thought I'd sell them.
In SE, this corresponds to video positions 01:22:28:21 and 01:22:30:09 (with SMPTE timing ticked).
If I go to 01:22:28:21 and untick SMPTE timing, the video position is now 01:22:33:20. If I go to 01:22:30:09 and untick SMPTE timing, the position is now 01:22:35:08.

If I then use Adjust speed in percent, the same subtitle now looks like:
Dialogue: 0,1:22:28.33,1:22:29.83
In SE, with SMPTE timing unticked, it runs between 01:22:28:08 and 01:22:29:20. With SMPTE ticked, it runs between 01:22:28:08 and 01:22:29:20. (Whereas it should be 01:22:33:20-01:22:35:08 with SMPTE unticked.)

[darnn]

After messing around in ChatGPT for a good while, it gave me this, which does perform the conversion correctly, if it helps:
sub2.py.txt
And this is what it gave me when I asked to convert it to C#, though I haven't tested it:
sub2.cs.txt