Integrate with PluggableUSB for native USB MIDI

[franky47]

It seems easier now to integrate with native USB for communications, so writing an interface for the library that uses native USB as transport protocol could be investigated.

Also, see #32.

[CaptainCredible]

Great news!

[franky47]

Good news: it's fairly simple to integrate with the MidiUSB Arduino library, there's still a bit of work to be done in midi_UsbTransport.hpp, but I'm already able to receive and send NoteOn/NoteOff messages.

Example: MidiUSB.ino

Bad news: the latency is terrible, but I was kind of expecting it. The issue here is that the wrapping around MidiUSB makes it double the work needed to receive a message.
ie: data arrives from USB bus, is pre-parsed by the MidiUSB library into midiEventPacket_t objects, then the MIDI library consumes it by re-transforming them into a serial stream.

[dmadison]

Has there been any progress on this since last year? I've been doing a bit of work on a MIDI project and I'd like to eventually integrate both USB MIDI and serial MIDI on the same board.

[marcosassis]

hey @franky47 , your library is great and beautiful, thanks very much for your work and attention, I really appreciate it

Bad news: the latency is terrible, but I was kind of expecting it. The issue here is that the wrapping around MidiUSB makes it double the work needed to receive a message.

but this problem is huge, and in my opinion it's a design bad choice in the basis of the library (which is yours or MidiUSB's creator I don't know...)

I'm new on MIDI and USB development, but I've been studying some things (I'm using pro micro at the moment, but I intend to be as generic as possible in my works, with some nice options already out-of-the-box)

I almost used your library's interface to MIDIUSB in my project (and honestly... I don't know how to say this), but I can't figure out what do I have to do to write/send a single MIDI note on this. my pro micro can play/send notes MIDI over MIDIUSB used directly (as in example MIDIUSB_write), but it doesn't works using midi::UsbTransport. and instead of trying to figure out what happened here and try to fix it on the promise of a bad latency on final, I'd prefer to study [more than I initially expected in this phase of my project] more MIDI and USB and re-write everything (maybe even including MIDIUSB functionality).

but, anyway, it seemed more reasonable to try to open this channel with you, so we can exchange important information and different points of view on the same problem.

please feedback us about this issue. I hope with some collaboration, we can or chose one way to do this together, or at least greatly improve each approach we choose to solve this.

best regards

[franky47]

Hi @marcosassis,

The midi::UsbTransport is the most naive way of connecting the current MIDI library (which works by parsing a byte stream) with the MIDIUSB library (which, as per the MIDI USB spec, works with packets), and was only made as an exploratory attempt to enable native USB capabilities. To be honest, it should probably not have ended up in the repository at all.

A more realistic approach to interfacing MIDI through both USB and Serial transports would probably require splitting the interface from the parser, having separate parsers for various transport types. The issue is that it may become less straightforward for beginner users to handle.

I'll have to check what options we have in the Arduino compilers to make this transparent to users.