routing MIDI data onto 2 or more MIDI Network Sessions fails

sounda

Hi there,

I try to route MIDI data from different apps running in the MIDI lanes of AudioBus3 to different MIDI Network Sessions (rtpMIDI Sessions) – but this does not work … is it bug of AB3 or a feature of iOS 😉?

I created 2 MIDI Network Session on my PC with rtpMIDI (https://www.tobias-erichsen.de/software/rtpmidi.html), they got the Bonjour names “musicHost” and “musicHost2” and my iPad is connected to both sessions as well (the connection is real as I see latency data when AudioBus3 starts and connects to these, respectively the coreMIDI subsystem) – both are also showing up in AB3s list of MIDI receiver, see image “AudioBus MIDI receiver.jpg”.

In AudioBus3 I setup 2 MIDI lanes, see also “AudioBus MIDI lane setup.jpg”
• Soundprism as input -> musicHost (renamed from Network Session 1 rtpMIDI) as output
• NaviChord as input -> musicHost2 (created in rtpMIDI) as output

If I play a chord in Navichord the MIDI Data are received on the PC through musicHost2, which is correct … but also through musicHost, which is not expected – see image “MIDI Monitor.png”
Or in other words: the data seems to be copied over / distributed to all MIDI Network sessions that the iPad is connected to.

Stranger than fiction – the same happens, if I eject musicHost as the output of the first MIDI Line – so from AudioBus point of view there is only musicHost2 … but same thing: the MIDI data of Navichord arrive on the PC through musicHost as well.

So I guess this is an iOS restriction that per device we can only use 1 MIDI Network Session and its an iOS behavior that copies the data over / merges them to all connected MIDI Network Sessions under the hood (fan out kind of feature) … but that’s only a guess … any real knowledge & wisdom on this is very much appreciated.

By the way, I know I could route both apps (Soundprism & Navichord) through 1 MIDI Network Session, each using only 1 specific MIDI channel – but this scenario is just for easy reproducing the problem and discussing about it.

My actual aim is to route the MIDI data of multiple MPE instruments from my iPad to a Windows PC into my DAW, each of the MPE instruments needing a separate MIDI Port, because each new note will be created on another MIDI channel and channel aftertouch messages will “describe” the expressive play of that note (and this is all about the awesome Touchscaper app and its MIDI out feature by the way), hence multiple MIDI Network Sessions.

I did already some explorations about that, but I want to share and discuss these in anther discussion in this forum, just to keep things separated – this MIDI Network Session / rtpMIDI session feature on iOS is a thing is of its own.

thanks & cheers
sounda

Michael

So I guess this is an iOS restriction that per device we can only use 1 MIDI Network Session and its an iOS behavior that copies the data over / merges them to all connected MIDI Network Sessions under the hood (fan out kind of feature) … but that’s only a guess … any real knowledge & wisdom on this is very much appreciated.

Yep, you're correct. A very strange limitation which has always baffled me. All we can do is use different MIDI channels to separate. It's pretty dumb though.

sounda

thanks @Michael ... not that great news, but that's the way it is.

Let's see & discuss if we can find another solution ... maybe some app developer gets inspired to create one.

For anyone whose interessted, here is the discussion : https://forum.audiob.us/discussion/39663/how-to-route-mpe-midi-from-the-ipad-to-pc