Estimating tempo and measure lengths

• Jul 14, 2020 - 22:31

I have some live performances recorded in the studio that I want to enhance with some bass lines and percussion. Since the performance is rubato, I will have to precisely adjust the tempo for each measure. I will need to have some method for calculating this. I can put the audio into a DAW and measure each measure of four beats in milliseconds, but how can I translate the milliseconds into the bpm tempo notation of Musescore, which measure bpm to the hundredth or thousandth of a second? Is there some formula that I could use with a calculator and get the most accurate result? The calculators available online are not all that precise. What's the formula?

Comments

• Jul 15, 2020 - 00:13

Honestly, don't bother creating this type of tempo map inside MuseScore.
Simply write your bass & percussion backing track out, then use your DAW to beat-sync it with your recording; where that should be a lot easier to do.

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• Jul 15, 2020 - 00:41

That's one method, and I've done something like this with some other project. I'd like to be able to use other methods. Just to have more in my toolkit. There must be a conversion formula for bpm to milliseconds and milliseconds to bpm. I don't know about beat sync. How does that work? I have used beat finder, but was not too impressed. I'm only using Audacity. Maybe you are using something more sophisticated?

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• Jul 15, 2020 - 01:04

I've used PreSonus Studio One for this (as it came "for free" with my digital mixer), but gathered that Ardour (free for real) should be quite up to that task as well.

The formula is fairly simple as soon as you realize that BPM in MuseScore is actually QPM (1/4th notes per minute):
60000 / milliseconds * timesig

So if you are working in a 2/4 measure and measure the time of one measure in milliseconds, you'd end up with:
60000 / milliseconds * 2 / 4
But if your timesig instead is 9 / 8:
60000 / milliseconds * 9 / 8

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• Jul 15, 2020 - 01:25

OK. So spose I want to measure a measure of four beats, or even just one beat, in milliseconds. I'll measure a section 6.399 milliseconds. How would that translate to bpm in Musescore? The suceeding section of "equal" length measures 6.35 ms. It won't hurt to round these numbers to 6.4 and 6.35.
How can I notate this so that Musescore is following the rubato measurement of the live audio track?

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• Jul 15, 2020 - 02:02

So this is what I did for the first calculation:
60000 ÷ 64000 × 4 ÷ 4 = 0.9375
The second is:
60000 ÷ 63500 × 4 ÷ 4 = 0.9448

Does this look right?

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