Hitchhiker's Guide to Openbsd

13.7 - How do I use my MIDI instruments?
The Musical Instrument Digital Interface (MIDI) protocol provides a standardized and efficient means to 
represent musical performance information as electronic data. A MIDI data contain only instructions 
needed by a synthesizer to play the sounds, rather than the sounds. More information: 
Tutorial on MIDI 
and Music Synthesis
. 
To play MIDI data, a synthesizer connected to a MIDI port of the machine is required. Similarly, to 
record a MIDI data a MIDI instrument is required (eg. a MIDI keyboard). Certain sound cards contain 
embedded MIDI synthesizers that are attached as MIDI ports. Advanced MIDI instruments may contain 
multiple subparts (synthesizers, keyboards, control surfaces, etc...), they appear as multiple MIDI ports 
on OpenBSD. 
When you already have OpenBSD running, look for MIDI ports in the output of the dmesg(8) command. 
An example of MIDI ports in a dmesg output is: 
umidi0 at uhub2 port 2 configuration 1 interface 0 "Roland 
Roland XV-2020" rev 1.10/1.00 addr 2
midi0 at umidi0:
umidi1 at uhub1 port 2 configuration 1 interface 1 
"Evolution Electronics Ltd. USB Keystation 61es" rev 
1.00/1.25 addr 3
midi1 at umidi1:
It shows three MIDI ports, corresponding to: 
●
/dev/rmidi0
- synthesizer connected by USB 
http://www.openbsd.org/faq/faq13.html (12 of 25)9/4/2011 10:02:21 AM

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13 - Multimedia
●
/dev/rmidi1
- a MIDI master keyboard 
These devices are known by 
sndio(7)
as 
rmidi:0
and 
rmidi:1
. To test your MIDI keyboard, you 
can use the 
hexdump(1)
utility to display MIDI data you're playing on it: 
$ midicat -q rmidi:1 -o - | hexdump -e '1/1 "%02x\n"'
90
3c
71
...
The output of the keyboard can be connected to the input of the synthesizer, as follows: 
$ midicat -q rmidi:0 -q rmidi:1
Now you can hear on the synthesizer what you're playing on the MIDI keyboard. Refer to the 
midicat(1)
manual page for further information. 
The main utility to play standard MIDI files is 
midiplay(1)
. Playing a standard MIDI file, in this 
example through the synthesizer, is as easy as: 
$ midiplay -f rmidi:0 file.mid
To record MIDI files, you can use the 
smfrec
utility bundled in the 
audio/midish
port, for 
instance: 
$ smfrec -d rmidi:0 -i rmidi:1 file.mid
will record what is played on the keyboard (
rmidi:1
) while sending it in real-time on the synthesizer 
(
rmidi:0
) so you can hear what you're playing. More complicated operations like editing, routing, 
mixing and transforming MIDI data, can be achieved using the 
rmidish
utility bundled in the 
audio/
midish
port.