another attempt to better remedy song transition for visualizer

core/src/zero1hd/rhythmbullet/audio/visualizer/VisualizerCore.java

@@ -39,15 +39,15 @@ public class VisualizerCore implements Disposable {
 	}
 	
 	public void setMM(MusicManager mm) {
+		lock.lock();
 		if (audioPCM == null || audioPCM.length != mm.getReadWindowSize()) {
 			calc = false;
-			lock.lock();
 			fft = new FloatFFT_1D(mm.getReadWindowSize());
 			audioPCM = new float[mm.getReadWindowSize()];
-			lock.unlock();
 		}
 		this.mm = mm;
 		calc = true;
+		lock.unlock();
 	}
 	
 	public void render(Batch batch, float parentAlpha) {