Getting Started With MIDI

I found that getting started with MIDI wasn't quite plug-and-play on Linux. Having no musical background, and no exposure to MIDI terms, it took a few Sunday mornings to get that first note to play out of a USB midi keyboard controller I borrowed from a friend.

My setup:

Ubuntu 8.04
vanilla alsa-compatible sound card, no wavetable or any fancy synth / midi capabilities of it's own
a Roland PCR-30 midi keyboard controller, which has no sound output of it's own

My goal:

Hit a key on the keyboard, and have it play out through my soundcard

I started with the gui shell for fluidsynth called 'qsynth', so:

 apt-get install fluidsynth qsynth

Since I don't have a wavetable or whatever it's called, I needed a 'sound font' to emulate one.

 apt-get install fluid-soundfont-gm

I launched qsynth, and by default it wanted to speak to jackd; I've never had jackd working correctly, it always produces crackling sound for me, so I clicked on 'setup', and changed hte audio driver to ALSA.

At this point, I used 'pmidi' to play a midi file out through the qsynth/fluidsynth MIDI device. You can see it by doing:

 $ pmidi -l
  Port     Client name                       Port name
  14:0     Midi Through                      Midi Through Port-0
 128:0     FLUID Synth (13710)               Synth input port (13710:0)

And so I played a song by doing:

 $ pmidi -p 128:0 <midi file>

Hurray! Sound! I plugged in the MIDI keyboard controller at this point, and was also able to see it in the output of pmidi listing:

 $ pmidi -l
  Port     Client name                       Port name
  14:0     Midi Through                      Midi Through Port-0
  20:0     PCR                               PCR MIDI
  20:1     PCR                               PCR 1
 128:0     FLUID Synth (13710)               Synth input port (13710:0)

So, I can see the midi keyboard controller, 20:0, and 20:1, and I can see a synthesizer, 128:0 -- now I wanted to connect the two together somehow. After some random searching, I saw a comment in a bug report about midi referring to 'aconnect', which is the 'ALSA sequencer connection manager', and had some example syntax: "aconnect 64:0 65:0".

That looked exactly like the sort of thing I wanted to do, and it appeared to see the devices I wanted to use:

 $ aconnect --input
 client 0: 'System' [type=kernel]
     0 'Timer           '
     1 'Announce        '
 client 14: 'Midi Through' [type=kernel]
     0 'Midi Through Port-0'
 client 20: 'PCR' [type=kernel]
     0 'PCR MIDI        '
     1 'PCR 1           '
     2 'PCR 2           '

 $ aconnect --output
 client 14: 'Midi Through' [type=kernel]
     0 'Midi Through Port-0'
 client 20: 'PCR' [type=kernel]
     0 'PCR MIDI        '
     1 'PCR 1           '
 client 128: 'FLUID Synth (13710)' [type=user]
     0 'Synth input port (13710:0)'

I first tried connecting 20:0 to 128:0, that produced no output. Then I tried 20:1 to 128:0:

 $ aconnect 20:1 128:0

I hit a key, and thought I heard a 'tink'. Or was that something outside? I turned up the volume on my stereo a bit, and at last, I had sound. It was playing a trumpet, which seemed to be left over from the midi file I played earlier. So I restarted qsynth, and reconnected the devices using aconnect, and it defaulted back to a piano.

References:

 * Getting Started with MIDI on Linux, a fellow in the same boat as me
 * Free MIDI music, handy for testing: http://www.mididb.com/

last edited June 22, 2008 — ( info ) ( diff )