Stretching subtitles with mkvmerge

Hi all.

I was wondering whether there was a mkvmerge equivalent to the “stretch by” option (under “Timestamps and default duration” in MKVToolnix). I do use this a lot for subtitles when converting files from one frame rate to another.

If I enter 23.976/25 into that field (for example) then it works really well - but it’s a manual job when I have many files and I’d like to automate it.

Many thanks all.

Kind regards.

From Mike.