I want to be able to use one Ableton project with different global tempos, but I want to preserve the tempo automation in the master track.
Essentially, I would like to have changes relative to the global BPM, but I would like the BPM values to be static. For example:
If I have a global tempo of 100bpm, I would like to add 4bpm at specific intervals to the track (e.g. 104bpm, 108bpm, 112bpm, etc).
If I change the global tempo to 160bpm, I still want the automation curves to add 4bpm at specific intervals to the track (e.g. 164bpm, 168bpm, 172bpm, etc).
It doesn't seem as though automation curves provide this functionality - there's no way to define a relative tempo change based on the absolute BPM change or the percentage of the current tempo.
Is there something that I've missed in terms of tempo changes? (For example, automating relative fader volume can be achieved by automating output gain on the Utility block, so a fader can be moved without losing automation.) Is this possible without using something like Max for Live? Is there a way to do this with a MIDI track?