In many cases, people can (from their synthesizer) send on two channels at once - they just don't realize it. 

If your synthesizer has the capability of doing a "split keyboard", which means designating part of the keyboard for one instrument, and the other part for another instrument, it has the capability of sending on two MIDI channels at the same time. 

There is probably another part of the MIDI setup where you designate the two MIDI channels used for each part of a split-keyboard.  My old Roland D20 synthesizer can even do a keyboard split.  My newer Yamaha S90-ES can do it, but it's has to do with setting up a custom voice. 

You could also test it by running vkeybd (the old virtual MIDI keyboard), along with VMPK.  Use both of them (rather than two instances of either) so you can tell them apart. 

When you click the "Manage MIDI Devices" toolbar button in Rosegarden, you will see the two virtual keyboard MIDI input devices.  Both virtual keyboards have a way of specifying which MIDI channel they send on. 

One other piece of information that might be helpful, is that I was using qjackctl, and qsynth (for the sound generation).  I don't know if that affected it.  I will run the same test using just my Soundblaster card (with its emu10k1 synthesizers) and see if that makes a difference, letting you know if it does. 

- Aere

On Tue, 2012-05-22 at 12:41 -0400, Tom Breton (Tehom) wrote:
> All:
> I've started trying out the version of Rosegarden distributed with
> Lubuntu 12.04, and encountered a problem.  I think the crash has already
> generated a bug-report, but with this e-mail, I'm hoping to give you a
> heads-up of the problem, and fill in a few more details.

So that's Lubuntu 12.04, released two weeks before our 12.04, and it has
Rosegarden 11.11.42.  I highlight this because our playthru code and some
sequencer/driver co-ordination did change in Rosegarden 12.04 (my
responsibility).  But you're experiencing that on 11.11.42

I can't reproduce it.  My keyboard only sends on one channel and I don't
get a crash.

I know you said you couldn't easily upgrade, and I don't want to hold out
too much hope that distantly-related changes somehow fixed it.  But if you
find you can upgrade, please let us know how it goes.  And thank you for
the bug report.

	Tom Breton (Tehom)