Calculate the time difference for video timecode (hrs:mins:secs:frames per second)

I'm sure this is an easy one and I've found plenty of posts about calculating time differences, but not in this specific case.

I'm trying to write a formula which automatically calculate the difference in video timecode for this specific format:

hrs:mins:secs:frames per second

Frames per second is 24.

So as an example:

01:05:33:21 - 01:04:04:15 = 00:01:29:06

Can anyone help?