from midi(4):

     The API for the sequencer device is binary compatible with the OSS
     sequencer interface.

So I didn't expect it to be too hard to get audio/rosegarden to
support midi output (after all, midiplay works) by building it with
-DSYSTEM_OSS instead of -DSYSTEM_SILENT.

But first it turns out the structs midi_info and synth_info are not
declared in <sys/soundcard.h>.  synth_info is easy to find, it's in
<sys/midiio.h>, mentioned on the man page. But that file doesn't
define midi_info, and the associated ioctl definition is commented out.

Is there a way to get equivalent functionality?

BTW, any projections on how near NetBSD is to being able to support
Rosegarden 4?  audio/rosegarden is currently at 2.1.4 which is long
dead (and can't use the sequencer anyway).  Rosegarden 4 relies on
ALSA, I believe.

-Chap