2 files changed, 17 insertions, 15 deletions

diff --git a/ext/mixed/js/audio-system.js b/ext/mixed/js/audio-system.js
index 7ae8efdc..19c85690 100644
--- a/ext/mixed/js/audio-system.js
+++ b/ext/mixed/js/audio-system.js
@@ -18,12 +18,13 @@
 /* global
  * CacheMap
  * TextToSpeechAudio
+ * api
  */
 
 class AudioSystem {
-    constructor({getAudioInfo, cacheSize=32}) {
-        this._cache = new CacheMap(cacheSize);
-        this._getAudioInfo = getAudioInfo;
+    constructor(useCache) {
+        this._cache = new CacheMap(useCache ? 32 : 0);
+        this._fallbackAudio = null;
     }
 
     prepare() {
@@ -81,6 +82,13 @@ class AudioSystem {
         throw new Error('Could not create audio');
     }
 
+    getFallbackAudio() {
+        if (this._fallbackAudio === null) {
+            this._fallbackAudio = new Audio('/mixed/mp3/button.mp3');
+        }
+        return this._fallbackAudio;
+    }
+
     createAudio(url) {
         return new Promise((resolve, reject) => {
             const audio = new Audio(url);
@@ -105,6 +113,10 @@ class AudioSystem {
 
     // Private
 
+    async _getAudioInfo(source, expression, reading, details) {
+        return await api.getDefinitionAudioInfo(source, expression, reading, details);
+    }
+
     _isAudioValid(audio) {
         const duration = audio.duration;
         return (
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index 3c7deefe..0b0236da 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -46,10 +46,7 @@ class Display extends EventDispatcher {
         this._options = null;
         this._index = 0;
         this._audioPlaying = null;
-        this._audioFallback = null;
-        this._audioSystem = new AudioSystem({
-            getAudioInfo: this._getAudioInfo.bind(this)
-        });
+        this._audioSystem = new AudioSystem(true);
         this._styleNode = null;
         this._eventListeners = new EventListenerCollection();
         this._setContentToken = null;
@@ -1234,10 +1231,7 @@ class Display extends EventDispatcher {
                 ({audio, index} = await this._audioSystem.createDefinitionAudio(sources, expression, reading, {textToSpeechVoice, customSourceUrl}));
                 info = `From source ${1 + index}: ${sources[index]}`;
             } catch (e) {
-                if (this._audioFallback === null) {
-                    this._audioFallback = new Audio('/mixed/mp3/button.mp3');
-                }
-                audio = this._audioFallback;
+                audio = this._audioSystem.getFallbackAudio();
                 info = 'Could not find audio';
             }
 
@@ -1569,10 +1563,6 @@ class Display extends EventDispatcher {
         return {type, expression, reading};
     }
 
-    async _getAudioInfo(source, expression, reading, details) {
-        return await api.getDefinitionAudioInfo(source, expression, reading, details);
-    }
-
     async _setOptionsContextIfDifferent(optionsContext) {
         if (deepEqual(this._optionsContext, optionsContext)) { return; }
         await this.setOptionsContext(optionsContext);