recently i looked into getting a keyboard midi controller. we already have a piano but a piano doesnt have ports, so, i looked into getting a keyboard. however, keyboards are expensive, and i would prefer NOT to spend hundreds - potentially thousands - of dollars on somthing that would just be a little convenience thing for when i write songs. so, now i had the idea to take a microphone, run the frequencies through a couple calculations and output a midi or usb signal compatible with musescore and maybe garageband. i would have some switches on top for whether to output notation or audio or none at all, and maybe a couple potentiometers for tune and stuff like that. im not very experienced with audio though, and have no idea how to give a usb signal, never mind one thats compatible with other programs.
as you can probably tell by my description, im quite inexperianced in this field. i would like advice on which calculations to use in order to round to a perfect frequency, how to give a usb signal (thats compatible with other programs), and maybe some part suggestions. thanks!
You've chosen one of the most difficult problems in audio. Even programs costing loads of money with the full resources of a top-end PC to work on only get it right about 85% of the time. Any real music note contains lots of different frequencies and just identifying them all then working out which one is supposed to be the "note" takes a lot more than "a couple calculations".
If you're talking about an electronic piano then maybe there is a way to get inside and work out which note is being pressed then go from there. That is done fairly often.
Each piano key does not produce a single note. Each one produces a complex pattern of many notes. When two keys are played at once, each produces it's own pattern of notes and a third pattern of notes is formed by the combination of the first two patterns. If 3 keys are played at once, 3 patterns of notes are produced and 3 more patterns are formed from each combination of 2 of the 3 notes. If 4 keys are played at once....
That couple of calculations probably turns out to be a couple of million calculations, and you need a university degree in maths to understand them.