> I think MIDI is very well suited to build on top of, without needing to change the spec. I disagree. I think MIDI uses a basic abstraction that's awkward fo

> I think MIDI is very well suited to build on top of, without needing to change the spec. I disagree. I think MIDI uses a basic abstraction that's awkward for anything that's not piano-like, and attempting to fix it by laying things on top just muddles things. MPE works around MIDI's limitations, but it's not a very clean interface. Users have to be aware of whether they're using MPE or not. If they are, channels don't work the same way as when they aren't. (And interestingly MIDI gets things wrong in about the same way that standard music notation fails.) I think MIDI's main mistake is that it assumes that a key, a note, a pitch, and a voice are all unique and be used to uniquely identify each other. So, for instance a keyboard can send NOTE-ON 72 127 when someone hits the C4 key at full velocity, and then when they release it the keyboard can send NOTE-OFF 72. There's this assumption that there's only one C4 being played at once, so the keyboard can just say, "stop playing the C4 note" to get it to stop. This breaks down if you send two NOTE-ONs for the same note in a row (which I think is technically allowed), but sending a NOTE-OFF when there are multiple notes playing is undefined behavior. The way most synths actually work internally is that you have one or more voice engines that can be tuned to any arbitrary note. I think a more sensible approach is to just have the controller allocate voices explicitly, and then tune them however it wants. Voices can be referenced by a unique ID that's independent of pitch. For instance, the controller might send messages like, "hey, I want to allocate a new voice which I will call V1; please set aside one voice engine and tune it to 261.63 hertz". The controller might do this before the user even hits a key. Then when the user hits a key it might send a command "please apply a percussive envelope to voice V1 using such and such parameters." When the user releases the key it might send a command "please apply an aggressive damping filter to voice V1". And so on. The controller might want to allocate more voices than the synthesizer actually has, but that's fine -- modern synths generally implement some notion of voice stealing anyways.