midi2osc/: simple MIDI to OSC forwarder

midi2osc/Makefile

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+CFLAGS = -Wall -g
+LDFLAGS = -lasound -llo
+
+.PHONY:		clean
+
+midi2osc:	midi2osc.c
+
+clean:
+		rm -f midi2osc

midi2osc/README

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+midi2osc register itself as a writeable MIDI device. It then forwards
+the MIDI messages it receives to the specified OSC destination.
+
+To use it with the Milkymist One,
+
+- enable Ethernet on the M1
+- ./midi2osc IP-address-or-host-name
+- launch qjackctl
+- click on the Connect button in qjackctl
+- in the "Connections" window, drag a connection from each MIDI device
+  you want to connect to midi2osc
+- MIDI events will now show up in the MIDI settings dialog, etc.

midi2osc/midi2osc.c

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+/*
+ * midi2osc.c - MIDI to OSC forwarder
+ *
+ * Written 2011 by Werner Almesberger
+ * Copyright 2011 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <alsa/asoundlib.h>
+#include "lo/lo.h"
+
+
+#define	NAME "midi2osc"
+
+
+static void forward(snd_seq_t *midi, lo_address osc)
+{
+	snd_seq_event_t *ev;
+	uint8_t msg[4] = { 0, };
+
+	while (snd_seq_event_input(midi, &ev)) {
+		switch (ev->type) {
+		case SND_SEQ_EVENT_NOTEON:
+			msg[1] = 0x90 | ev->data.control.channel;
+			msg[2] = ev->data.note.note;
+			msg[3] = ev->data.note.velocity;
+			break;
+		case SND_SEQ_EVENT_CONTROLLER:
+			msg[1] = 0xb0 | ev->data.control.channel;
+			msg[2] = ev->data.control.param;
+			msg[3] = ev->data.control.value;
+			break;
+		case SND_SEQ_EVENT_PITCHBEND:
+			msg[1] = 0xe0 | ev->data.control.channel;
+			msg[2] = ev->data.control.value;
+			msg[3] = 0;
+			break;
+		default:
+			/* Flickernoise currently doesn't support any others */
+			snd_seq_free_event(ev);
+			continue;
+		}
+		if (lo_send(osc, "/midi", "m", msg) < 0)
+			fprintf(stderr, "%s\n", lo_address_errstr(osc));
+		snd_seq_free_event(ev);
+	}
+}
+
+
+static void usage(const char *name)
+{
+	fprintf(stderr, "usage: %s hostname [port]\n", name);
+	exit(1);
+}
+
+
+int main(int argc, char **argv)
+{
+	const char *port = "4444";	/* Milkymist One OSC port */
+	lo_address osc;
+	snd_seq_t *midi;
+
+	switch (argc) {
+	case 2:
+		break;
+	case 3:
+		port = argv[2];
+		break;
+	default:
+		usage(*argv);
+	}
+
+	osc = lo_address_new(argv[1], port);
+	if (!osc) {
+		fprintf(stderr, "invalid address %s %s\n", argv[1], port);
+		exit(1);
+	}
+
+	if (snd_seq_open(&midi, "hw", SND_SEQ_OPEN_INPUT,0) < 0) {
+		fprintf(stderr, "can't open ALSA sequencer\n");
+		exit(1);
+	}
+	snd_seq_set_client_name(midi, NAME);
+	if (snd_seq_create_simple_port(midi, NAME,
+              SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE,
+              SND_SEQ_PORT_TYPE_APPLICATION) < 0) {
+		fprintf(stderr, "can't create sequencer port\n");
+		exit(1);
+	}
+
+	forward(midi, osc);
+
+	return 0;
+}