Fix ordering of NoteOn Vel=0 events (#908)

include/fluidsynth/seq.h

@@ -47,7 +47,7 @@ extern "C" {
  * @param data User defined data registered with the client
  *
  * @note @p time may not be of the same tick value as the scheduled event! In fact, depending on
- * the sequencer's scale and the synth's sample-rate, @p time may a few ticks too late. Although this
+ * the sequencer's scale and the synth's sample-rate, @p time may be a few ticks too late. Although this
  * itself is inaudible, it is important to consider,
  * when you use this callback for enqueuing additional events over and over again with
  * fluid_sequencer_send_at(): If you enqueue new events with a relative tick value you might introduce

src/synth/fluid_event.c

@@ -142,10 +142,18 @@ fluid_event_timer(fluid_event_t *evt, void *data)
  * @param channel MIDI channel number
  * @param key MIDI note number (0-127)
  * @param vel MIDI velocity value (0-127)
+ * @note Since fluidsynth 2.2.2, this function will give you a #FLUID_SEQ_NOTEOFF when
+ * called with @p vel being zero.
  */
 void
 fluid_event_noteon(fluid_event_t *evt, int channel, short key, short vel)
 {
+    if(vel == 0)
+    {
+        fluid_event_noteoff(evt, channel, key);
+        return;
+    }
+
     evt->type = FLUID_SEQ_NOTEON;
     evt->channel = channel;
     evt->key = key;
@@ -176,10 +184,11 @@ fluid_event_noteoff(fluid_event_t *evt, int channel, short key)
  * @param evt Sequencer event structure
  * @param channel MIDI channel number
  * @param key MIDI note number (0-127)
- * @param vel MIDI velocity value (0-127)
+ * @param vel MIDI velocity value (1-127)
- * @param duration Duration of note in the time scale used by the sequencer (by default milliseconds)
+ * @param duration Duration of note in the time scale used by the sequencer
  *
  * @note The application should decide whether to use only Notes with duration, or separate NoteOn and NoteOff events.
+ * @warning Calling this function with @p vel or @p duration being zero results in undefined behavior!
  */
 void
 fluid_event_note(fluid_event_t *evt, int channel, short key, short vel, unsigned int duration)

test/test_seq_evt_order.c

@@ -12,7 +12,7 @@ int main(void)
     fluid_event_set_time(evt1, 1);
     fluid_event_set_time(evt2, 1);
 
-    // double negation below, because we want to check for leftIsBeforeRight, however, event_compare() returns !leftIsBeforeRight
+    // Note that event_compare() returns !leftIsBeforeRight
 
     TEST_ASSERT( !event_compare_for_test(evt1, evt1));
     TEST_ASSERT( !event_compare_for_test(evt2, evt2));
@@ -28,12 +28,26 @@ int main(void)
     TEST_ASSERT(!!event_compare_for_test(evt1, evt2));
     TEST_ASSERT( !event_compare_for_test(evt2, evt1));
 
-    fluid_event_noteon(evt1, 0, 0, 0);
+    fluid_event_noteon(evt1, 0, 0, 60);
     fluid_event_noteoff(evt2, 0, 0);
 
     TEST_ASSERT(!!event_compare_for_test(evt1, evt2));
     TEST_ASSERT( !event_compare_for_test(evt2, evt1));
 
+    // make sure noteons with vel=0 are handled like noteoffs
+    fluid_event_noteon(evt1, 0, 0, 60);
+    fluid_event_noteon(evt2, 0, 0, 0);
+
+    TEST_ASSERT(!!event_compare_for_test(evt1, evt2));
+    TEST_ASSERT( !event_compare_for_test(evt2, evt1));
+
+    // two noteoffs
+    fluid_event_noteon(evt1, 0, 0, 0);
+    fluid_event_noteoff(evt2, 0, 0);
+
+    TEST_ASSERT( !event_compare_for_test(evt1, evt2));
+    TEST_ASSERT( !event_compare_for_test(evt2, evt1));
+
     fluid_event_unregistering(evt1);
     fluid_event_system_reset(evt2);