Improve audio and midi support.

src/audio/midi/MidiTrack.h

@@ -1,15 +1,30 @@
 #pragma once
 
 #include <vector>
+#include <memory>
+#include <string>
 #include "MidiEvent.h"
 
+class MidiEvent;
+using MidiEventPtr = std::unique_ptr<MidiEvent>;
+
 class MidiTrack
 {
-	std::vector<MidiEvent> mEvents;
-
 public:
 
-	MidiTrack();
+    MidiTrack();
 
-	void AddEvent(const MidiEvent& event);
+    ~MidiTrack();
+
+    void AddEvent(MidiEventPtr event);
+
+    MidiEvent* GetEvent(std::size_t idx) const;
+
+    std::size_t GetNumEvents();
+
+    std::string Serialize() const;
+
+private:
+
+    std::vector<MidiEventPtr> mEvents;
 };