Logic Pro X Creating a Tempo Map to a Recorded Song

seanmccoy

Logician
Hey all. I've been given a song to add an arrangement onto, and am having a heck of a time creating a tempo map without messing up the existing audio. The song has a main acoustic guitar track, several additional guitars that enter later, and a boatload of vocal tracks that come in and out. It's a slow song with pretty lousy time, but I just need to get it in the ballpark. Logic was able to create a reasonably close map using the main guitar, but all of the later entrances were out of sync. I tried the old-fashioned method of playing a click, and again Logic matched that very well, but again it messed up the sync. I've tried it with Flex on, Flex off, Adjust Tempo, Automatic Tempo, Keep Tempo, and nothing works to prevent the audio regions from sliding around. What am I missing here? How can I create a map to match the performance without wrecking the performance?
 

fuzzfilth

Logician
So you have a project containing several tracks, each with regions which start anywhere throughout the song, right ?

- disable Flex on every track
- look for the earliest region that suggests tempo (might well be that acoustic guitar track)
- look for the first discernable note on that track
- select all regions and nudge them all at once so that this first note lies on a matching position of the musical grid (downbeat on a downbeat, or eight-note-pickup on 4+ of the bar)
- select just the guitar track and its regions
- open Global Tracks>Beat Mapping
- select Analyze Transients from the Beat Mapping popup menu. This will give you lots of blue transient markers
- click the first transient marker to lock the start position
- now work our way through the song, pulling transient markers to bar lines, like this:

map.gif


One marker per bar should be fine, maybe two if there are actual rits or accs. Creating a solid tempo map will take roughly twice the running time of the song, less if you're fast.
 
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seanmccoy

Logician
Thanks for the tutorial! I've done quite a lot of work with Flex Time (and Elastic Audio), so the process doesn't seem daunting, but it does seem strangely complex. I'll report back.
 
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seanmccoy

Logician
Well, that kinda, sorta worked. This track is so syncopated, and the time is so whacked, that it was a nightmare trying to determine which transients to move to the bar lines in many cases. So while this will still help with my arranging since most of the downbeats are now downbeats, the tempo map is all over the place, and quantization won't really be an option. Shouldn't be a problem since there won't be any drums or percussion on this one anyway. Thanks for the instruction. I'm sure this will come in handy in the future.
 
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