Thanks, tlw. There's definitely going to be some Tap Tempo tomfoolery as well but mostly to get an approximate tempo to set the project to. What I'm attempting to do is actually manually time stretch everything into proper time because it just fluctuates too and then I can do more finite work like getting individual drum hits and guit/bass start/stops lined up.
 
What I'm thinking so far is this.
 
a) Get the project timeline map with the right sigs and tempo for the material (and I may do some tempo map tricks for dynamics... like intentional speed ups and what not).
 
b) Snip up all the tracks of each song in sections (there are two takes of each song both recorded without a click so they are nowhere near matched up). These cuts will be made across all the tracks so I can keep everything sync'd up as I stretch. The cuts will depend on the material but they may occur at measures or at the ends of full riff sections.
 
c) Then I'd link all the clips by section. The first clip would obviously start on the 1st beat and lined up to a measure. Time stretch the end of clip section one (so all linked clips for that section follow) so that the end matches up with a measure. Drag clip section 2 (and all clips linked to it) to but up against clip1. Rinse repeat for the whole song.
 
d) Go back through and make sure it all sounds normal and do any x-fading that needs to be done between the clip sections and bounce.
 
Now I've got an in time song that matches the timeline. I can then do the finite audio snap work to correct off hits and instruments played out of time.
 
Because there is a second set of tracks for each song I can then match those up with the now time corrected versions and raid them for overdubs or created doubled parts.
 
I've done some experiments on other material and I think this should work but it's going to be an epic feat and I definitely need to make sure the timeline/project is set up properly or it'll get real f*cky real fast. lulz... I know because I tried this a couple years back using the TOTALLY wrong method and it was a nightmare that ended up in shreiks and further hairline recession.
 
Of course I have many other reasons for wanting to know this stuff (like I claim to be a musician) but this has definitely been on my mind.
 
Cheers.

The easiest way to think about it is,
 
1 Measure at 4/4 = 4 quarters x 4 measures is 16 beats.
 
7/8 is 56 beats however takes the same musical time of 7/4 (28 beats).
 
Assuming the tempo is 120 bpm, the one crotchet (1/4) is 250ms , 1/8 is 125ms etc.
 
For five notes ins 4/4 time, you could use 3 single hits, 1 beam 1/8th notes to make up the 1/4.
 
Understanding how the MIDI input is translated is key to understanding how to quickly manipulate things.