I am using macOS Big Sur 11.0.1 on a MacBook Pro. I have Audacity 2.4.2. I need to convert mp3 and mp4 files to MIDI in order to play them on a Samick SG-450 Digital Ensemble Grand. A little help?
mp3 and mp4 files
Are they mixed song files? I’m not sure anybody can do that. MIDI isn’t a sound format. It’s machine control. MIDI has to know which instrument, what note, how loud, how long, and sustain. For every note. On each instrument.
Some software packages might be able to create a MIDI performance out of a single instrument playing single notes in a quiet studio.
Current Audacity can’t do any of that.
If you do come up with a way that works post back. This comes up every so often.
Koz
What koz said.
Also, do a google search for an mp3 to midi converter on the web. There are a few. I had occasion many many years ago to try this. I was very dissatisfied with the results. I doubt if they have made much improvement, but if so, please post back. 
Actually, I’d recommend searching for “audio to MIDI”.
I’ve never tried it but I’m “highly skeptical” that you can get useful results with “normal music” where you have multiple different instruments & voices playing;/singing multiple-simultaneous-different notes & chords all at the same time…
Thanks for everyone’s input. Sounds like this may be impossible. One thing: it’s not multiple instruments, voices, etc. It’s only piano. Will that make a difference?
Does the performance ever hit two or more notes at once? That’s the end of the world.
Manufacturers did a terrific, bang-up job of fooling everybody into thinking MIDI is a sound format. Somebody sends you a MIDI song and you play it on your computer, right? That’s what it looks like you’re doing. Actually, you’re running their MIDI program and it’s playing the instruments inside your computer out to your headphones. If you have the right software, you can make a MIDI song play the same tune with different instruments.
Try that with an MP3.
Is the whole job live performing against someone else’s backing track? You know Audacity can do overdubbing, right? Depending on your kit, you can do simple or perfect overdubbing where you hear yourself plus the backing tracks mixed in your headphones.
Koz
Can you do some research on the internet and let us know what you find out. We would love to be proven wrong.
If it is only one note at a time, there are “Audio to MIDI” programs that can do that quite well.
It’s been a few years since I’ve looked closely, but as far as I’m aware this is still the case:
If there are multiple notes playing at the same time (as is typical with piano music) there will probably be lots of errors - “phantom” notes added that are not in the original audio, some notes missing, and some wrong notes. The best (and most expensive) audio to midi apps are getting better, but even the best will usually require a lot of manual correction.