oscmix

oscmix implements an OSC API for RME's Fireface UCX II running in class-compliant mode, allowing full control of the device's functionality through OSC on POSIX operating systems supporting USB MIDI.

Current status

Most things work, but still needs a lot more testing, polish, cleanup. Some things still need to be hooked up in the UI or implemented in oscmix.

Supported devices

• RME Fireface UCX II

Usage

oscmix [-dl] [-r recvaddr] [-s sendaddr]

oscmix reads and writes MIDI SysEx messages from/to file descriptors 6 and 7 respectively, which are expected to be opened.

By default, oscmix will listen for OSC messages on udp!127.0.0.1!7222 and send to udp!127.0.0.1!8222.

See the manual, oscmix.1, for more information.

Running

Linux

On Linux systems, you can use bundled alsarawio program open and configure a given raw MIDI subdevice and set up these file descriptors appropriately.

To determine your MIDI device, look for it in the output of amidi -l (the one ending in ,1 with the name Fireface UCX II).

For example:

alsarawio 2,0,1 oscmix

There is also a tool alsaseqio that requires alsa-lib and uses the sequencer API.

To determine the client and port for your device, find it (port 1 of the Fireface UCX II) in the output of aconnect -l.

For example:

alsaseqio 24:1 oscmix

BSD

On BSD systems, you can launch oscmix with file descriptors 6 and 7 redirected to the appropriate MIDI device.

For example:

oscmix 6<>/dev/rmidi1 7>&6

GTK UI

The gtk directory contains oscmix-gtk, a GTK frontend that communicates with oscmix using OSC.

To run oscmix-gtk without installing, set the GSETTINGS_SCHEMA_DIR environment variable.

GSETTINGS_SCHEMA_DIR=$PWD/gtk ./gtk/oscmix-gtk

Web UI

The web directory contains a web frontend that can communicate with oscmix through OSC over a WebSocket, or by directly to an instance of oscmix compiled as WebAssembly running directly in the browser.

The web UI is automatically deployed at https://michaelforney.github.io/oscmix.

It is tested primarily against the chromium stable channel, but patches to support other/older browsers are welcome (if it doesn't complicate things too much).

Also included is a UDP-to-WebSocket bridge, wsdgram. It expects file descriptors 0 and 1 to be an open connection to a WebSocket client. It forwards incoming messages to a UDP address and writes outgoing messages for any UDP packet received. Use it in combination with software like s6-tcpserver or s6-tlsserver.

s6-tcpserver 127.0.0.1 8222 wsdgram

To build oscmix.wasm, you need clang supporting wasm32, wasm-ld, and wasi-libc.

OSC API

The OSC API is not yet final and may change without notice.

TODO Document rest of API. For now, see the OSC tree in oscmix.c.

Contact

There is an IRC channel #oscmix on irc.libera.chat.