Can Live Automate the Tempo Based on a MIDI Track?

[Tranceophile]

Hi folks,

I'm running Live 9 Suite and I'm wondering whether I can use it in a way that complements my playing habits. Specifically, when I compose a song I almost always improvise with the right hand playing some melody, and the left hand repeating a bass pattern that long ago became second nature (1-5-8-5... e.g., C2-G2-C3-G2...) Now, the left-hand part is just there for me to give a record of any key changes, and because over the years I've gotten in the hard-to-break habit of playing it. Once I've got the melody down, I'd like to go back, nuke the bass line, and replace it with something more interesting than just the same old 1-5-8-5 over and over again. But that turns out to be very difficult to do for improvisations of any appreciable length, because I play without the metronome or caring what the BPM is set to -- indeed, I find myself gradually varying the tempo, in accord with the feel I want to give the music. If I try to replace the bass line with patterns I later design, I get left- and right-hand parts that play out of synch, unless I painstakingly craft a bass line pattern that is as long as the improvisation itself.

It occurs to me that I could exploit the regularity of my boring bass line as a source of MIDI events supplying dynamic rhythmic information. This information would be used to somehow automate the tempo of the arrangement to slow down and speed up so that, for example, the "1" in the "1-5-8-5" would always fall on the first beat of the measure. Once I'd achieved that, I could get rid of the bass line: the synchronization with the melody would be captured in the automation of the tempo. I could go back and insert bass clips I had designed, and they would play aligned with the rhythm of the melody.

Does Ableton 9 have this capability out of the box? I have a feeling this could be a nice project for learning how to program in Max for Live, but hey, there's no use in reinventing the wheel if it already exists.