Logic Pro X Recording Slow, Then Speeding Up

seanmccoy

Logician
Hey, all. I've got an upcoming project that will involve a clarinetist performing all 11 parts of a composition. He's created time signature maps (gazillions of changes), and will of course be playing to a click, but he's informed me some sections are impossible for him to play at tempo, so we'll need to slow the some of the tempos down for recording. I use Logic almost exclusively for MIDI composition, so this is new territory for me. I've read through some threads similar to this and come away with no consensus. What's the currently recommended method for the least amount of artifacts?
 

fuzzfilth

Logician
- Make sure the section to be sped up will be recorded separately
- Lower the tempo just enough that he can adequately play it. Speeding up more than absolutely necessary will make the cheat clearly audible.
- If you have a Tempo Map with more than one entry, duplicate that Tempo Map and adjust the Tempo Change(s) for that section accordingly, so you can switch back and forth between record- and playback-tempo.
- Prepare a second track to record the slowed down parts, then engage GlobalFlex View at 1, then Track Flex at 2 (monophonic will be fine) and finally Region Flex at 3:

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- If you restore the original Tempo, these parts will speed up.
- Record all the slowed down parts to that track, all the normal parts to a regular, unflexed track.
 
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bayswater

Logician
I've done this with guitar and bass parts now and then. It would probably be easier with a clarinet, but to do it without artifacts is pretty difficult if not impossible. For example, the envelop of the sound is sped up along with the tempo, so attacks and releases happen faster, and any vibrato, tremolo or natural pitch variations move faster. There are a lot of plugins that can treat these things to manipulate attacks, or correct pitch variation, but these might just add as many artifacts as they remove.

I think it's unlikely that an experienced player of the instrument will be convinced by the result unless the tempo change is minimal. At some point it might be better to just use a VI with samples and speed up the MIDI tempo. If what you're producing doesn't exist in a real world of music, one source of artifact might be preferable to another.
 
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seanmccoy

Logician
Yeah, it's a quandary because the whole point of the project is him doing all the parts of this complex piece by himself. Fortunately he's been experimenting so he understands what we're up against here. I've already warned him about the oddities of unnatural note transitions when speeds are radically changed, but thanks for reminding me that any type of modulation will be even more wacko. Hopefully he won't likely be trying to use vibrato or other effects during passages that are so fast he can't play them at tempo. I have a feeling by the time this is over, I'll be more familiar with all of Logic's time shifting capabilities (and probably Melodyne) than I ever wanted to be.
 
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bayswater

Logician
A quandary in many ways. Playing with no vibrato/tremolo/volume variations at all will sound very dull and artificial, and too much of any of these will be captured in the tempo changes and also sound strange. It will be a challenge to strike the right balance. Maybe you can come back and report what you learn about how to do this sort of thing.
 
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seanmccoy

Logician
He'll be free to use vibrato and other expressions where needed, as the plan is to only slow down the sections that are wall-to-wall 16th notes, not entire pieces. I'll definitely report back on how things go.
 
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