I have a MOTU MTP AV. This is one "device" in alsa, but it has eight MIDI ins and outs.

You can get something similar if you want to test this by loading the snd-virmidi device into your Linux kernel (you are running Linux, aren't you?).

I start up PD with -mididevs 1,2,3,4,5,6,7,8 thinking I'm going to get eight MIDI ports. Never mind that I'm going to have to suffer away with midiin and midiout rather than the nicer midi objects. Here's what happens:

[jfm3@localhost opatch]$ sudo pd -alsa -rt -mididev 1,2,3,4,5,6,7,8 -noaudio couldn't open MIDI input device 1 couldn't open MIDI input device 2 couldn't open MIDI input device 5 couldn't open MIDI input device 6 couldn't open MIDI input device 7 couldn't open MIDI input device 8 couldn't open MIDI output device 1 couldn't open MIDI output device 2 couldn't open MIDI output device 5 couldn't open MIDI output device 6 couldn't open MIDI output device 7 couldn't open MIDI output device 8 opened 2 MIDI input device(s) and 2 MIDI output device(s). Using ALSA interface retrying connect... priority 98 scheduling enabled. memory locking enabled. priority 96 scheduling enabled. memory locking enabled.

Notice that only two MIDI "devices" are recognized. One of these is my MTP AV and the other is the Virtual MIDI driver. Sure enough, if I poke around at a midiout object for long enough, I find that "device 3" corresponds to MIDI in and out #1 on the MTP AV, and that "device 4" corresponds to MIDI in and out #1 on the Virtual MIDI driver. I can't get at any of the other ports, which makes me depressed.

If I run alsa-patch-bay and connect the first Virtual MIDI driver port to the second port on the MTP AV, I can get MIDI on two of the ports in the MTP AV. Furthermore, I can play back on all twelve (or more!) ports in MusE or Rosegarden, so I know it's not a driver or hardware issue.

Do I need to dig out the Pd source and stare at this for a while, or am I missing something?

(jfm3)