main process: provisional decoding of midi messages

delay.c

@@ -8,7 +8,7 @@ void delay_init(
     struct delay * delay
 ) {
     delay->mix = 0.8;
-    delay->feedback = 0.6;
+    delay->feedback = 0.8;
     delay->duration = 0;
     delay->buf_idx = 0;
     delay->buf_capacity = 0;

guitfx.c

@@ -75,15 +75,37 @@ static void on_process(void *userdata, struct spa_io_position *position)
 						char * midi_data = SPA_POD_BODY(&c->value);
 						unsigned size = SPA_POD_BODY_SIZE(&c->value);
 
+						printf("[%d] MIDI message (%d bytes) : %x, %x, %x\n", sec, size, midi_data[0], midi_data[1], midi_data[2]);
+
+						switch( midi_data[0] & 0xff ) {
+						    case 0xb0:
+								switch( midi_data[1] ) {
+									case 0x0b:
+									    // expr pedal
+										float val_f = ((float)midi_data[2]) / 128.0;
+										printf("Expr Pedal %f\n", val_f);
+
+										data->delay.mix = val_f;
+									    break;
+
+								    case 0x42:
+										// sust pedal
+
    									    uint64_t cur_tap = frame + c->offset;
     									uint64_t duration = cur_tap - data->last_tap;
     									data->last_tap = cur_tap;
-
-						printf("duration = %lu\n", duration);
     									if( duration < (4*position->clock.rate.denom) ) {
-						  delay_set_time( &data->delay, duration );
+    									  delay_set_time( &data->delay, duration/4 );
+    									}
+										break;
+								}
+								break;
+
+							case 0xc0:
+							    // program change
+								printf("program change: %u\n", midi_data[1]);
+							    break;
 						}
-						printf("[%d] MIDI message (%d bytes) : %x, %x, %x\n", sec, size, midi_data[0], midi_data[1], midi_data[2]);
 					} else {
 					    printf("on_process(): non midi-control\n");
 					}