use AudioContext.currentTime + DECAY_TIME to debounce sound start

Debounce when the sound starts to keep from playing many copies of the same sound layered on itself. Use AudioEngine's currentTime in seconds plus some value in milliseconds to make sure the sound has a chance to start before starting a second playback.
scratchfoundation · Jun 21, 2018 · 2126761 · 2126761
1 parent 331f083
commit 2126761
Showing 1 changed file with 14 additions and 11 deletions.
diff --git a/src/GreenPlayer.js b/src/GreenPlayer.js
@@ -31,10 +31,18 @@ class SoundPlayer extends EventEmitter {
 
         this.initialized = false;
         this.isPlaying = false;
-        this.isStarting = null;
+        this.startingUntil = 0;
         this.playbackRate = 1;
     }
 
+    /**
+     * Is plaback currently starting?
+     * @type {boolean}
+     */
+    get isStarting () {
+        return this.isPlaying && this.startingUntil > this.audioEngine.audioContext.currentTime;
+    }
+
     /**
      * Handle any event we have told the output node to listen for.
      * @param {Event} event - dom event to handle
@@ -147,7 +155,7 @@ class SoundPlayer extends EventEmitter {
         const taken = new SoundPlayer(this.audioEngine, this);
         taken.playbackRate = this.playbackRate;
         if (this.isPlaying) {
-            taken.isStarting = this.isStarting;
+            taken.startingUntil = this.startingUntil;
             taken.isPlaying = this.isPlaying;
             taken.initialize();
             taken.outputNode.disconnect();
@@ -170,7 +178,7 @@ class SoundPlayer extends EventEmitter {
         }
         this.volumeEffect = null;
         this.initialized = false;
-        this.isStarting = null;
+        this.startingUntil = 0;
         this.isPlaying = false;
 
         return taken;
@@ -205,12 +213,7 @@ class SoundPlayer extends EventEmitter {
 
         this.isPlaying = true;
 
-        const isStarting = this.isStarting = Promise.resolve()
-            .then(() => {
-                if (this.isStarting === isStarting) {
-                    this.isStarting = null;
-                }
-            });
+        this.startingUntil = this.audioEngine.audioContext.currentTime + this.audioEngine.DECAY_TIME;
 
         this.emit('play');
     }
@@ -227,7 +230,7 @@ class SoundPlayer extends EventEmitter {
         this.outputNode.stop(this.audioEngine.audioContext.currentTime + this.audioEngine.DECAY_TIME);
 
         this.isPlaying = false;
-        this.isStarting = null;
+        this.startingUntil = 0;
 
         this.emit('stop');
     }
@@ -243,7 +246,7 @@ class SoundPlayer extends EventEmitter {
         this.outputNode.stop();
 
         this.isPlaying = false;
-        this.isStarting = null;
+        this.startingUntil = 0;
 
         this.emit('stop');
     }