如何将Midi从Java程序发送到OSX上的IAC总线

Question

I'm trying to write a program that will send MIDI messages to external synthesizers. It does work when using the default synth in Java (1.8 on a mac) and makes a nice ping sound every second when connected to the default synthesizer in Java. As expected this is a boring sound, but it does verify that I'm able to make short midi sequences that are interpreted as sounds by a synth.

I then try to route that signal to an IAC device, so that it can be picked up by other programs (including synthesizers) that can make interesting sounds. However, it seems that none of the events I produce are actually picked up by the IAC device. It doesn't seem like they are sent outside of the JVM, or if they are they are somehow dropped.

My question is simply: Has anyone done this, and can they tell me what they did?

In essence my code does this:

final MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo();
for (int i = 0; i < infos.length; i++) {
       final MidiDevice device = MidiSystem.getMidiDevice(infos[i]);

       final String  deviceInfo = device.getDeviceInfo().getName();

       // My IAC device is called "Bus 1"
       if ("Bus 1".equals(deviceInfo)) {

          Receiver rcvr = device.getReceiver()
          ShortMessage myMsg = new ShortMessage();
          // Start playing the note Middle C (60),
          // moderately loud (velocity = 93).
         myMsg.setMessage(ShortMessage.NOTE_ON, 0, 60, 93);
         rcvr.send(myMsg, timeStamp);
       }
  }

I the test this by connecting the IAC device to an MS-20 soft synth, no sounds are produced. I then connect a "MockMidi" keyboard up to the "Bus 1" IAC device, and I can then play the MS-20 bus. I then try to hook the MockMidi keyboard up to the Bus 1 as an input device, but I don't see any events.

Looks straightforward, but as far as I can tell, no midi messages are ever received at the IAC device when sent from Java, yet the mechanism seems to be working fine both inside java, and outside Java.

I'm stuck, all help will be highly appreciated (and source code will be shared on github when it works (sending to IAC would count as working)). :-)

Answer 1

The documentation for getReceiver() says:

Obtaining a Receiver with this method does not open the device. To be able to use the device, it has to be opened explicitly by calling open() .