What's the formula to change AudioEffectPitchShift in order to have all the notes ?

MonsieurBouboule

Hey there! I have a question that's probably silly but since I both absolutely suck at math and music theory, I thought I might as well try to find your help.

Say I have a sound in my project, and that sound is a piano sound the plays the C note, for example. Now, I want to use the AudioEffectPitchShift effect of an audiobus to change that C into the next note on a piano (here that's C#), what would be the value of "pitch scale" (knowing that by default the note is a C and the pitch scale is 1) ? Then, what if I want it to be the next note, so a D in that example, what would be the value of the pitch_scale ? And so on and so on... I'm sure there's a formula (obviously), and I tried to find it on the internet but on wikipedia or music websites, it usually becomes impossible to understand for me, very quickly. The only thing I found was this : pow(2, (n/12)) but I have no idea if it's the thing I'm looking for or how to use it in code...

Can someone be kind enough to give me the formula or the values I'm supposed to set in the AudioEffectPitchShift for every note please (so 12 values I guess) ?

Thanks a lot four your help :)

MizunagiKB

That's exactly what the formula for the musical scale is.

pow(2, (n/12))

This formula is determined by something called the law of averages. https://en.wikipedia.org/wiki/Equal_temperament

I'm not going to explain music theory here, because it would take too long to explain, but I'll focus on how to play a note with Godot. I'll just talk about how to play sounds with Godot.

I think a diagram is easier to understand than text, so I've made a simple diagram. （I've made a simple diagram (with specific code)

func play_pianosound(note: float):
    var pitch = pow(2, note/12.0)
    $piano.stop()
    $piano.pitch_scale = pitch
    $piano.play()

I hope this will be useful for your development.

MonsieurBouboule

That’s such a helpful answer, thanks a lot! I’ll try the formula soon enough.