You would think after lord knows how many years I would finally understand this implementation but dagnabbit if I'm not still flummoxed by how obtuse it is.
Example: I've got a multitrack song I'm doing a remix for. Recorded w/o a click. Okee, so I pull up one of the acoustic guitar tracks, which has the strongest rhythm components in it. I show transients, I bring up the audiosnap pallette. I select the clip. I select "edit clip map" and get to work. Now luckily for me I ALREADY trimmed the snot out of the tracks, so 1:1 is right at the start of the song. I've had tons of probs with what is basically an "intro" with little to no tempo info totally screw this process up.
Anyhow, I start moving beat markers around and dropping them on the correct places. I hit "set project from clip" to line up what I've got so far. Now the rest of the markers don't auto-stretch to find their "best guess" homes. Ugh. That means going through THE WHOLE SONG and mapping it out. Well, I guess that's okay, time well spent since there's a HUGO tempo change about 2/3 of the way through and I want a strong grid to manhandle this folky ditty into a trip-hop behemoth. I get to the tempo change, and now SONAR tells me the tempo is "out of range" and can't handle the new tempo. Eesh! And since the first few bars of the new section are a little loosey I can't "skip ahead" to drop measure markers because I need to count out every beat from left to right. Ugh.
I wish there was a more elegant and non-linear way to approach attaching transient markers to measure and beats and establishing the tempo relationship. Just for kicks I threw the tracks into Live and was instantly able to muck with the tempo and get results close to what I wanted. Sure, there was some skittering on the beats because the track is a waltz and I left it at 4/4 but heck if it wasn't CLOSE.
I know this kind of processing and manipulation is not the easiest thing in the world, and with tons of parameters to consider there's no "Fix It" button...but darned if after several years of trying to audiosnap things I still can't get it working quite right. Even AFTER watching some great user-created youtube vids on it.