Added Visualized song player and required playlist modifications (untested).

Class names and respective file names refactored.

Added song player for basic playlist management and playback.

Added support for visualizers per song in the playlist.

Created a visualizer update manager that acts as a splitter for all the bins and their updates.

Fixed potential bugs.

src/player/PlaylistSong.js

@@ -1,3 +1,4 @@
+import Visualizer from "../Visualizer";
 import SongPlaylist from "./SongPlaylist";
 
 /**
@@ -17,8 +18,9 @@ export default class PlayListSong {
         this._displayName = name;
         this._author = author;
         this._url = url;
-        this._audio = null;
         this._playlist = playlist;
+        this._audio = null;
+        this._visualizer = null;
 
         /**
          * Whether or not this song is ready to be played.
@@ -40,7 +42,6 @@ export default class PlayListSong {
         if (this._audio) {
             if (this.ready) {
                 if (onReady) onReady(this._audio);
-                return this._audio;
             }
             return this._audio;
         }
@@ -91,7 +92,7 @@ export default class PlayListSong {
      * 
      * @returns {boolean} true if and only if there is audio data that is either already loaded or is being loaded.
      */
-    audioInstantiated() {
+    isAudioInstantiated() {
         return this._audio ? true : false;
     }
 
@@ -108,7 +109,7 @@ export default class PlayListSong {
      * Pauses the audio playback, unless the audio data has yet to be instantiated.
      */
     pause() {
-        if (!this.audioInstantiated()) return;
+        if (!this.isAudioInstantiated()) return;
         this.getAudio((audio) => {
             audio.pause();
         });
@@ -157,9 +158,37 @@ export default class PlayListSong {
      * Unloads the audio data.
      */
     unloadAudio() {
-        if (!this.audioInstantiated()) return;
+        if (!this.isAudioInstantiated()) return;
         this._audio.pause();
+        this.unloadVisualizer();
         this._audio = null;
         this.ready = false;
     }
+
+    /**
+     * 
+     * @param {number} [fftSize=1024] the size of the FFT window.
+     * @returns {Visualizer} returns the visualizer.
+     */
+    getVisualizer(fftSize = 1024) {
+        if (this._visualizer && this._visualizer.getFftSize() === fftSize) return this._visualizer;
+        this._visualizer = new Visualizer(this.getAudio(), fftSize);
+        return this._visualizer;
+    }
+
+    /**
+     * 
+     * @returns {boolean} returns true if and only if the visualizer is instantiated.
+     */
+    isVisualizerInstantiated() {
+        return this._visualizer ? true : false;
+    }
+
+    /**
+     * Unloads the visualizer.
+     */
+    unloadVisualizer() {
+        this._visualizer.stop();
+        this._visualizer = null;
+    }
 }