Added midi-rx.c simple program that can pass ALSA sequencer MIDI events to pipe ...

diff --git a/c/ghetto-sound-system/Makefile b/c/ghetto-sound-system/Makefile
index 6e1cac871bce81329d1cba991873cb91ed8b1965..260a436f3aaacf0e120881a0581b6ab6224b9232 100644 (file)
--- a/c/ghetto-sound-system/Makefile
+++ b/c/ghetto-sound-system/Makefile
@@ -1,5 +1,5 @@
 sdl_BIN=sampler synth
-alsa_BIN=beatdetect
+alsa_BIN=beatdetect midi-rx
 
 #sdl_CFLAGS+=-lSDL_sound -lSDL -lSDL_mixer
 sdl_CFLAGS+=$(shell sdl-config --cflags --libs) -lSDL_mixer

diff --git a/c/ghetto-sound-system/midi-rx.c b/c/ghetto-sound-system/midi-rx.c
new file mode 100644 (file)
index 0000000..7ee730e
--- /dev/null
+++ b/c/ghetto-sound-system/midi-rx.c
@@ -0,0 +1,79 @@
+/* Modified code from http://tldp.org/HOWTO/MIDI-HOWTO-9.html
+ * This will print ALSA-Seq (MIDI) events to stdout for further processing eg.: in Arduino
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <alsa/asoundlib.h>
+
+#define MIDI_NOTE_OFF  128
+#define MIDI_NOTE_ON   144
+#define MIDI_CONTROL   176
+#define MIDI_PITCH_BEND        224
+#define MIDI_FORMAT    "%d:%d:%d\n"
+
+snd_seq_t *open_seq();
+void midi_action(snd_seq_t *seq_handle);
+
+snd_seq_t *open_seq() {
+
+  snd_seq_t *seq_handle;
+  int portid;
+
+  if (snd_seq_open(&seq_handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
+    fprintf(stderr, "Error opening ALSA sequencer.\n");
+    exit(1);
+  }
+  snd_seq_set_client_name(seq_handle, "ALSA Sequencer Pipe");
+  if ((portid = snd_seq_create_simple_port(seq_handle, "ALSA Sequencer Pipe",
+            SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE,
+            SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {
+    fprintf(stderr, "Error creating sequencer port.\n");
+    exit(1);
+  }
+  return(seq_handle);
+}
+
+void midi_action(snd_seq_t *seq_handle) {
+
+  snd_seq_event_t *ev;
+
+  do {
+    snd_seq_event_input(seq_handle, &ev);
+    switch (ev->type) {
+      case SND_SEQ_EVENT_CONTROLLER:
+        printf(MIDI_FORMAT, MIDI_CONTROL, ev->data.control.channel, ev->data.control.value);
+        break;
+      case SND_SEQ_EVENT_PITCHBEND:
+        printf(MIDI_FORMAT, MIDI_PITCH_BEND, ev->data.control.channel, ev->data.control.value);
+        break;
+      case SND_SEQ_EVENT_NOTEON:
+        printf(MIDI_FORMAT, MIDI_NOTE_ON, ev->data.control.channel, ev->data.note.note);
+        break;
+      case SND_SEQ_EVENT_NOTEOFF:
+        printf(MIDI_FORMAT, MIDI_NOTE_OFF, ev->data.control.channel, ev->data.note.note);
+        break;
+    }
+    snd_seq_free_event(ev);
+  } while (snd_seq_event_input_pending(seq_handle, 0) > 0);
+}
+
+int main(int argc, char *argv[]) {
+
+  snd_seq_t *seq_handle;
+  int npfd;
+  struct pollfd *pfd;
+
+  seq_handle = open_seq();
+  npfd = snd_seq_poll_descriptors_count(seq_handle, POLLIN);
+  pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd));
+  snd_seq_poll_descriptors(seq_handle, pfd, npfd, POLLIN);
+
+       fprintf(stderr, "COMMAND:CHANNEL:NOTE\nCommands are described on http://www.ec.vanderbilt.edu/computermusic/musc216site/MIDI.Commands.html\n\n");
+  while (1) {
+    if (poll(pfd, npfd, 100000) > 0) {
+      midi_action(seq_handle);
+    }
+  }
+}