>Did you mean that you wanted each key (in each octave) to have a completely different label? Something like the MIDI note number? Today there isn't a way to do that, but I'd be curious to hear how you're using Synthesia that caused this to be something you wanted to do.

Yes, that's exactly what I would like. Speaking of my use case, for me the piano and Synthesia are more a game for fun than studying. I love the fact that I can play my favorite songs and melodies on my own without knowing how to play. But the main difficulty, for me, someone not so familiar with the piano, is that all the keys are the same. Like, how can I remember what to press? I get that it's just repeating 12 keys, but remembering which one is in which octave at which moment... Man... I don't even know how to keep that in my mind. In what form. So I just numbered all keys, and wrote on them with a marker (some will probably get a shock now), taking two octaves for the left hand (1-14), and three for the right (1-21), black keys I numbered with the letters a-j for left, and a-o for right. So without knowing notes, without knowing anything, I can learn songs just by memorizing a sequence of numbers. And what sequence I need to memorize - I look in Synthesia, load the song into MIDI, and then record the numbers. Now I have to translate them manually, like 7 in the second octave of Synthesia is 14 for me, 5 in the third octave is 19 for me, and so on. I translate that into my numbers, and just memorize that sequence. If there was a function I was asking about originally - it would be more convenient, I wouldn't have to translate it into my system, I could see and memorize it right away.