[LAU] ALSA ate my MIDI! (Or Something)

[Matthew Smith]

Hi Folks

Just when I thought that everything was going well, I have hit a 
problem.  I have disabled the hd-intel sound card on my laptop to get 
rid of Jack xruns - which it did.

Since doing that, I have had some issues with the Alsa configuration; 
although I thought everything was supposed to hotplug, it appeared that 
Alsa was still looking for the hd-intel card.  This may just be a Gentoo 
quirk.

Alsaconf doesn't work with USB devices, which makes it pretty useless, 
so I had to wade through some configuration files and change lines so 
that that the modprobe aliases for card0 went to snd-usb-audio.  With a 
bit more fiddling and a couple of reboots, I got audio working again 
with my external Behringer sound card.

So far, so good.

Now, for some strange reason, MIDI seems to be broken.  When I plug in 
my Roland PC-300 MIDI controller and hook it up with Jack to a softsynth 
or to Rosegarden, nothing happens.  I flipped the switch on the back 
that sets the output to go to the 'real' MIDI port rather than through 
the USB system, hooked it into a 'real' synth module and it worked fine.

This is what my ALSA setup looks like:

Advanced Linux Sound Architecture Driver Version 1.0.15 (Tue Nov 20 
19:16:42 2007 UTC).

/proc/asound/devices:

   0: [ 0]   : control
   1:        : sequencer
  16: [ 0- 0]: digital audio playback
  24: [ 0- 0]: digital audio capture
  32: [ 1]   : control
  33:        : timer
  40: [ 1- 0]: raw midi


/proc/asound/cards:

  0 [default        ]: USB-Audio - USB Audio CODEC
                       Burr-Brown from TI
                       USB Audio CODEC  at usb-0000:00:1d.0-2, full s
  1 [PC300          ]: USB-Audio - PC-300
                       Roland PC-300 at usb-0000:00:1d.7-3.4, full speed


I dont' think that the PC-300 is broken because a) it is recognised and 
b) works OK when directed to its MIDI port.

Although all the Jack connections LOOK correct, no MIDI data gets from 
the keyboard to wherever I'm sending it.  (That includes doing a 
loopback through Jack so that the PC-300 inbound is connected to its 
hardware MIDI out.)

My suspicion is that ALSA is to blame but how and why, I have no idea.

I notice another ALSA quirk - if I fire up alsamixer, it only shows the 
playback channel of my USB sound device, not the capture channel. 
Running this with the hd-intel card, I see all channels.

Ideas, anyone?

Cheers

M

-- 
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
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