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Old 05-12-2021, 05:25 PM   #1
DrFrankencopter
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Default How do I split a midi item into a new item...for quantizing

Not sure I have the right terminology on this one...

But how do I split a midi item so the only contents of the split item are the notes from the parent item I split?

I have midi drums recorded from an E-kit, but not against a click, and now I want to grid them to a constant tempo as a guide track. I've split them up into one bar measures. Instead of just setting a constant tempo and quantizing I would rather adjust the tempo of each measure to best match the desired tempo of 133 BPM.

But if I take a one bar slice (which I had set to ignore project tempo in source properties), and change the tempo Reaper seems to adjust the tempo of the parent item the one bar slice was taken from (which spans several takes).

Is there any way to just adjust the playback tempo for the midi displayed in the one bar item itself?

Please say yes there is....I'm finding this super frustrating.
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Old 05-12-2021, 05:36 PM   #2
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Said another way...is there any way that I can split a midi track so that the split item ONLY contains the notes in the original split. I want it to forget its ties back to the original track it was split from.
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Old 05-12-2021, 05:40 PM   #3
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Or alternatively...stretch markers in Midi would let me do exactly what I'm looking to do. But alas inserting a stretch marker on a midi track seems to do....nothing
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Old 05-12-2021, 05:50 PM   #4
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Or is there a way I can select a bunch of midi notes and gradually change their position (tempo) in the midi editor.

Am looking to do subtle quantizing here...
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Old 05-12-2021, 11:21 PM   #5
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Why not just stretch your "1 bar slice" so that it fits a measure at (your desired tempo)

i.e. make your slices, set the project tempo & (alt-drag edges?) stretch the bits to fit?

Incidentally, if you want the quantisation to be "subtle", longer "slices" might be an idea - 2 bars? 4?
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Old 05-13-2021, 02:11 AM   #6
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I'm not sure I understand what you're trying to achive, but maybe you think too complicated. I answered in your post there.

If you want you can post (or mail) your MIDI-Drum Recording and I try to Tempo-Map it for you, just to show what's possible. The new Tempo-mapped file then contains your original (varying) tempo and from there you can work easily in every direction.
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Old 05-13-2021, 07:14 AM   #7
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Quote:
Originally Posted by zacki View Post
I'm not sure I understand what you're trying to achive, but maybe you think too complicated. I answered in your post there.

If you want you can post (or mail) your MIDI-Drum Recording and I try to Tempo-Map it for you, just to show what's possible. The new Tempo-mapped file then contains your original (varying) tempo and from there you can work easily in every direction.
Thanks for your answer in the other thread...I hadn't seen itt.

I have used this technique, and it does a good job of establishing a tempo map for a track that was not performed to a click. In fact, I have done this on the track that I'm working with. This method with the SWS 'Convert proj markers to tempo markers' nicely adds stretch markers in all my other audio tracks; I quite like this feature.

This definitely gets the click lined up with the performance...but now I'm looking to tighten up those tempo shifts

The back story is that I recorded a tune that my band was just putting together, and it was all done free time in a jam (e-Drums, bass, gtr, vocals). Since we are in lockdown now I'd like to make the best of the performance that is there, fix up some of the tempo drifts, properly record the guitars/bass, and have an idea of what drum parts may need to be overdubbed. I want to start by turning the drum performance into a bed track that I will build th re-recording around.

What I'm looking to do (at first) is to put the project to a constant tempo (133 BPM). So I've been going measure-by-measure and changing the tempo markers to 133, and then snapping the stretch markers in the audio tracks to the nearest measure. Then I need to go each measure of the midi E-drums and effectively change the tempo to best line up with the new tempo of 133 BPM.

I tried going to 'source properties' and changing the tempo there under "ignore project tempo and use XXX BPM", but the problem with this is that changing this setting adjusts the tempo for all the midi of the underlying item, not just the tempo of one measure midi item.

But, what I found is that I can adjust the "playback rate" under item settings for the one measure midi item and this only affects the midi within the item boundaries itself. It's a bit of a pain though because playrate is a ratio (i.e. newPlaybackTempo/originalTempo), so I need to mess around with playback rates that are like 1.003 (for example) whereas ideally I'd just type in the desired new tempo. But...it does work! I adjust the playback rate to best line up the midi notes with the grid line by typing in the playback rate sort of 'empirically'.

You might wondering "Why not just quantize to the new tempo", but if you think about it for a bit Quantize is great for fixing random timing errors around a fixed tempo, but it's not the right way for fixing underlying tempo issues. If the measure was played at a slower tempo than the desired tempo then doing say a 50% quantize over the measure will still have the last beats of the measure being slower than desired...the rhythm will 'drag' over the measure. Instead, you want to fix the tempo first so the hits approximately line up right with the new tempo, and then you can Quantize to taste. Hope that makes sense and clarifies what I'm trying to do.
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Old 05-13-2021, 07:16 AM   #8
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Quote:
Originally Posted by jrk View Post
Why not just stretch your "1 bar slice" so that it fits a measure at (your desired tempo)

i.e. make your slices, set the project tempo & (alt-drag edges?) stretch the bits to fit?

Incidentally, if you want the quantisation to be "subtle", longer "slices" might be an idea - 2 bars? 4?
I think I can't do this since the original piece was recorded at a different project tempo and I had to set the source properties of the midi to 'ignore project tempo' so it plays back correctly. I'll give it a shot this eve though.

Thanks for the 'longer slice' suggestion...I'll definitely keep that in mind.
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