Fix MPEChannelAssigner sometimes deregistering the wrong note

modules/juce_audio_basics/mpe/juce_MPEUtils.cpp

@@ -84,15 +84,29 @@ int MPEChannelAssigner::findMidiChannelForNewNote (int noteNumber) noexcept
     return midiChannelLastAssigned;
 }
 
-void MPEChannelAssigner::noteOff (int noteNumber)
+void MPEChannelAssigner::noteOff (int noteNumber, int midiChannel)
 {
-    for (auto& ch : midiChannels)
+    const auto removeNote = [] (MidiChannel& ch, int noteNum)
     {
-        if (ch.notes.removeAllInstancesOf (noteNumber) > 0)
+        if (ch.notes.removeAllInstancesOf (noteNum) > 0)
         {
-            ch.lastNotePlayed = noteNumber;
-            return;
+            ch.lastNotePlayed = noteNum;
+            return true;
         }
+
+        return false;
+    };
+
+    if (midiChannel >= 0 && midiChannel < 17)
+    {
+        removeNote (midiChannels[midiChannel], noteNumber);
+        return;
+    }
+
+    for (auto& ch : midiChannels)
+    {
+        if (removeNote (ch, noteNumber))
+            return;
     }
 }
 

modules/juce_audio_basics/mpe/juce_MPEUtils.h

@@ -65,8 +65,11 @@ public:
 
     /** You must call this method for all note-offs that you receive so that this class
         can keep track of the currently playing notes internally.
+
+        You can specify the channel number the note off happened on. If you don't, it will
+        look through all channels to find the registered midi note matching the given note number.
     */
-    void noteOff (int noteNumber);
+    void noteOff (int noteNumber, int midiChannel = -1);
 
     /** Call this to clear all currently playing notes. */
     void allNotesOff();