I now understand what you don't get from my perspective.
Imagine you have a timing section starting at 1:00.000 that is PERFECT, you won't ever touch that, ok?
Now imagine your first time section starts at 0:02.500, and you have a certain BPM. You're supposed to have the last white tick of your first section
equal to the first of the 1:00.000 section for one simple reason:
they both represent the same beat.
Do yo agree with me until now? (I hope so
)
Now, let's say you figure out that you're first section starts a little late, because the first beat is actually at 0:02.450. Now you have to change the offset of your first section, and sadly, the last tick of this section will be at 0:59.950, NOT 1:00.000, and it will not match the music. What's the solution then? Adjusting the BPM to this small change, that is recompute the BPM, either basing yourself on the number of beats, or by using the arrows (which is almost precise but quite as much), or by multiplying your previous BPM by (old duration of the section)/(new duration of the section) (this is equivalent to counting the number of beats in a way. It's just doing a ratio of the forumula involving the number of beats, but since the number of beat doesn't change it simplifies out, so do the '60').
In either cases,
you have to change the BPM, and do it manually is OK, BUT
it could EASILY be done automatically.
Actually, if the "counting the number of beats" is disturbing you, I think another way to implement this would be solely basing the computation on the previous duration of the section and the new duration. This would also work.
Thanks for continuing answering, so that the potential miscommunication can be overcome
By the way, you indicated on my map's thread that it should be single BPM, I totally don't agree, and if you're sure, I would like to see the BPM/offset you propose for your single section, so people (including me) could try and see what it gives. Thanks.