[LAU] midi sub-devices in OSS emulation

Brent Busby brent at keycorner.org
Mon Apr 9 17:55:56 CEST 2018

And not wanting to reply to my own post...but this whole subject has
brought up the question of what all these midi device nodes are anyway.
For certain ones, there doesn't seem to be a lot of documentation online
that I've been able to find.

On my system, I have:

--8<---------------cut here---------------start------------->8---
brent at village:~/.dosemu/run$ aconnect -o -l
client 14: 'Midi Through' [type=kernel]
    0 'Midi Through Port-0'
client 20: 'Hammerfall DSP' [type=kernel,card=1]
    0 'HDSP MIDI 1     '
client 28: 'UM-3' [type=kernel,card=3]
    0 'UM-3 MIDI 1     '
    1 'UM-3 MIDI 2     '
    2 'UM-3 MIDI 3     '
client 32: 'Virtual Raw MIDI 4-0' [type=kernel,card=4]
    0 'VirMIDI 4-0     '
client 33: 'Virtual Raw MIDI 4-1' [type=kernel,card=4]
    0 'VirMIDI 4-1     '
client 34: 'Virtual Raw MIDI 4-2' [type=kernel,card=4]
    0 'VirMIDI 4-2     '
client 35: 'Virtual Raw MIDI 4-3' [type=kernel,card=4]
    0 'VirMIDI 4-3     '
brent at village:~/.dosemu/run$ find /dev -name "*midi*"
--8<---------------cut here---------------end--------------->8---

ALSA is putting its prefered devices under /dev/snd/, but only the
virtual devices are showing up there all four times.

But the others...hmm...  What is the difference between midi, dmmidi,
amidi, and admmidi?

I think I might be able to route a connection with ALSA MIDI from the
subdevice of the USB interface I want to one of the virtual ports, and
then just use that virtual port's dev node, but even if that solution
works, the curious cat in me still wants to know what all these nodes
are for just to know, and also whether it's possible to directly expose
subdevices of hardware with multiple i/o's to the OSS emulation so the
subdevices show up in /dev.

- Brent Busby	+ ===============================================
		+ "The introduction of a new kind of music must
-- Studio    --	+  be shunned as imperiling the whole state, for
-- Amadeus/  --	+  styles of music are never disturbed without
-- Keycorner --	+  without affecting the most important political
-- Recording --	+  institutions."    --Plato, "Republic"
----------------+ ===============================================

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