I'm working on this remix of a song. Challenges? It's in waltz-time, and it has a coda that shifts to 4/4 (and picks up the pace quite a bit). I want to map a grid to it so I can program MIDI to it.
 
The first thing I tried was splitting the clips where the big tempo change happens so I'm just working with the waltz-time part. No probz. I tried dragging a clip up to the timeline and SONAR thinks about it for some time and then produces a very inaccurate map. Sigh.
 
So I dump that idea and start editing the tempo map of the main guitar part, which is the most accurate track to determine tempo to. But now I'm back to square one, plodding through the clip beat by beat to try and line it up. Once I'm done (assuming successful), I would then select "Set Project from Clip" in the audiosnap palette? 
 
But I'm still wondering if the new fancy schmancy melodyne method will work with non 4/4 material. Anyone have experience trying this out?
 

Hi. Maybe try to open the clip in Melodyne, and choose Percussive algorithm. Then try to drag the clip up to the timeline. (I have tried it on a non 4/4 recording (7/8 IIRC)) Hope it helps.
All the best.
Edit: I do not think that it captures time signature, only tempo. Others may know better.

...wicked
But I'm still wondering if the new fancy schmancy melodyne method will work with non 4/4 material. Anyone have experience trying this out?
 

You don't specify which version of Melodyne you have.  Version 4 of Editor or Studio supports what you are trying to accomplish.
Version 2 and Version 4 Essential do not contain a Tempo mapping editor and are hit or miss.
 
As an exercise to learn the tempo mapping tools in Melodyne 4, I tempo mapped a CD rip of the the Beatles' cover of A Taste of Honey.  The song starts with a rubato 3/4 and continues with verses in 3/4.  The chorus switches to 4/4.  There is another rubato section that lasts for 2 bars in 4/4 just before the ending of the song.
 
After reading the Tempo Editor in Assign Tempo Mode section in the Melodyne 4 online help thoroughly, I viewed two excellent YouTube videos on Melodyne 4 tempo mapping posted by jpettit123.  These videos use Studio One, but the concepts are the same in Sonar since both utilize ARA.
 
Melodyne 4 and Studio One Basic Tempo Mapping:  https://www.youtube.com/watch?v=oCvJOo7LLFw
 
Melodyne 4 and Studio One Advance Tempo Mapping:  https://www.youtube.com/watch?v=OADVEYXRq28
 
Melodyne did a very respectable job of determining the tempo in the non-rubato sections, but required manual adjustment in the Tempo editor for the rubato sections.  Time signature changes were entered manually in the Melodyne Tempo editor.  The corresponding time signature changes will have to be manually added to Sonar after the completed Tempo map is imported into Sonar.  When I was done, I had a very good tempo map of the song.
 
Hope this helps,
Ron

My recommendation:
 
Manually build the tempo map using Set Measure/Beat At Now (Shift+M), and enter meter changes as necessary. A more automated method might be worth learning/perfecting if you're generating multiple tempo maps every week, but if it's just a one-time or occasional need, the 'brute force' method will probably end up being just as fast and more precise (and cheaper if you don't already own Melodyne 4 Editor or Studio).
 
Audiosnap - Set Project From Clip can do it also, but you'll spend just as much or more time massaging the clip tempo map as you would manually setting beats, and it forces you to set a tempo every beat or bar and only on whole beats where Set Measure lets you set exactly as many or as few points as are necessary (including fractions of beats) to get good alignment. Also, I don't like that Audiosnap's tempo changes don't end up right on the M:B:T beat lines (a problem dating back to X1).

I have to say, Shift+M and Tab sets you up for a pretty fast workflow for mapping, thanks!
 
Here's an interesting new conundrum though: I mapped out the track this way, tabbing to transients and setting Measure/Beat at Now. But when I program percussion to it you can really hear the tempo fluctuations in a non-pleasant way. Sounds great in the original, undetectable or even pleasurable that way with a little swing in it. 
 
What I'd like to do now is go the other way, and snap the tempo back to a straight meter (3/4) so the drums sound more natural. How do I (presuming using Audiosnap) flatten the swing out back into a straight meter grid?
 

If you want to straighten out the original track, you'll need to enable Clip Follows Project in Autostretch mode on the audio, and then edit the tempos in the tempo view to reduce the variation or delete them to completely flatten them. If I'm understanding the project, the original track isn't going to continue to be part of the project so stretching quality won't be an issue.