midisndiokontrol

by Morgan Aldridge morgant@makkintosshu.com

OVERVIEW

A WIP (work in progress) utility that lets you control sndio devices & state, plus X11 media applications, under OpenBSD using a MIDI control surface. It's currently being developed & tested with a Korg nanoKONTROL2 (hence 'kontrol' in the name), but I plan to make it much more generic and configurable. It is currently just a wrapper around OpenBSD's midicat(1), sndioctl(1), xdotool(1), but I expect to rewrite it in C once I have stabilized the concept more, for performance reasons.

IMPORTANT: I am not a regular user of MIDI devices, nor have I delved into the spec yet, so I'm likely using incorrect terminology at this point. Please feel free to suggest corrections/improvements."

FEATURES

CURRENT

midisndiokontrol can currently handle MIDI CONTROL CHANGE "Expression" (CC11) messages from the Korg nanoKONTROL2 and trigger:

• X11 key, keyup, or keydown events for various standard XF86Audio* media keys (via xdotool)
• Set, unset, or toggle mute for sndio devices (via sndioctl)
• Set a knob/slider value as the level for a sndio input, output, or application device (via sndioctl)

The script is currently relatively straightforward to modify for your specific MIDI input device, sndio devices, and X11 applications. I suggest:

1. Run midicat -d -q midi/<device_num>
2. Press a key on your MIDI input device
3. Look at the 2nd column of hex output in the output of Step 1 to determine the key hex code
4. Edit the appropriate key_* variable content and set it to the hex code you identified
5. Update the "$key_*") handler in the case statement for the appropriate key to perform the action you'd like
6. Go to Step 2 and repeat until you've updated as you see fit

PLANNED

• Rewrite in Perl
• Make more configurable, especially the following for any MIDI key input:
  • MIDI key hex ID
  • Event type (i.e. "key", "down", "up", "value")
  • Action type (i.e. xdotool, sndioctl, etc.)
  • Action parameters (e.g. key <name>, keydown <name>, keyup <name> for xdotool or <device>.level=<value> or <device>.mute=<value> for sndioctl)
• Add support for panning audio in sndioctl(1) by calculating/adjusting the individual levels for stereo devices (e.g. sndioctl -i <device>.level[0]=<value_left> <device>.level[1]=<value_right>; with the device 'level' assumed to equal 'level[0] + level[1]' if 'level[0]' != 'level[1]')
• Monitor sndioctl -m output for device value state changes and send MIDI commands to control surface to illuminate buttons, as appropriate (e.g. on Korg nanoKONTROL2, when LEDs set to 'external': illuminate 'play' button when playing and maybe pulse/flash when paused, illuminate fast-forward/rewind buttons while depressed, illuminate 'mute' buttons for individual input/output devices when they are muted, etc.)
• Create defaults for various devices
• Rewrite in C for increased performance
• Port to other platforms which support sndio

PREREQUISITES

• OpenBSD
• A MIDI device
• xdotool

USAGE

1. Install xdotool: doas pkg_add xdotool
2. Connect your MIDI device
3. Either use midicat(1) to send your MIDI device's input to midithru/0 as follows, or update the midisndiokontrol script to specify the specific MIDI device to use: midicat -q midi/0 -q midithru/0 &
4. Execute midisndiokontrol to start it processing MIDI events and triggering sndioctl changes or xdotool keyboard input events

SIMILAR UTILITIES

You might want to check out these similar projects for controlling OpenBSD's sndiod(8) from X11:

• sndiokeys
• xsndiomenu

RESOURCES

• MIDI
• MIDI CC Lists & Explanations

LICENSE

Released under the MIT license.