refactor: rearrange getOrCreateMediaElementSourceAndUpdateMap

src/entry-points/content/AllMediaElementsController.ts

@@ -36,7 +36,9 @@ import type { keydownEventToActions } from '@/hotkeys';
 import broadcastStatus from './broadcastStatus';
 import once from 'lodash/once';
 import debounce from 'lodash/debounce';
-import { mediaElementSourcesMap } from '@/entry-points/content/audioContext';
+import {
+  mediaElementSourcesMap
+} from '@/entry-points/content/getOrCreateMediaElementSourceAndUpdateMap';
 import {
   lastPlaybackRateSetByThisExtensionMap, lastDefaultPlaybackRateSetByThisExtensionMap,
   setPlaybackRateAndRememberIt

src/entry-points/content/ElementPlaybackControllerCloning/ElementPlaybackControllerCloning.ts

@@ -32,8 +32,10 @@ import VolumeFilterNode from '@/entry-points/content/VolumeFilter/VolumeFilterNo
 import lookaheadVolumeFilterSmoothing from './lookaheadVolumeFilterSmoothing.json'
 import {
   audioContext as commonAudioContext,
-  getOrCreateMediaElementSourceAndUpdateMap
 } from '@/entry-points/content/audioContext';
+import {
+  getOrCreateMediaElementSourceAndUpdateMap
+} from '@/entry-points/content/getOrCreateMediaElementSourceAndUpdateMap';
 import {
   setPlaybackRateAndRememberIt,
   setDefaultPlaybackRateAndRememberIt,
@@ -363,7 +365,10 @@ export default class Controller {
         if (BUILD_DEFINITIONS.BROWSER === 'gecko') {
           const mozCaptureStreamUsed = !unprefixedCaptureStreamPresent;
           if (mozCaptureStreamUsed) {
-            const mediaElementSource = getOrCreateMediaElementSourceAndUpdateMap(element);
+            const [, mediaElementSource] = getOrCreateMediaElementSourceAndUpdateMap(
+              element,
+              () => commonAudioContext
+            );
             mediaElementSource.connect(commonAudioContext.destination);
           }
         }

src/entry-points/content/ElementPlaybackControllerStretching/ElementPlaybackControllerStretching.ts

@@ -19,7 +19,10 @@
  */
 
 import browser from '@/webextensions-api';
-import { audioContext, getOrCreateMediaElementSourceAndUpdateMap } from '@/entry-points/content/audioContext';
+import { audioContext } from '@/entry-points/content/audioContext';
+import {
+  getOrCreateMediaElementSourceAndUpdateMap
+} from '@/entry-points/content/getOrCreateMediaElementSourceAndUpdateMap';
 import {
   getRealtimeMargin,
   getOptimalLookaheadDelay,
@@ -291,7 +294,10 @@ export default class Controller {
       });
     }
 
-    const mediaElementSource = getOrCreateMediaElementSourceAndUpdateMap(element);
+    const [, mediaElementSource] = getOrCreateMediaElementSourceAndUpdateMap(
+      element,
+      () => audioContext
+    );
     let toDestinationChainLastConnectedLink: { connect: (destinationNode: AudioNode) => void }
       = mediaElementSource;
     if (this.isStretcherEnabled()) {

src/entry-points/content/audioContext.ts

@@ -27,19 +27,3 @@ export const audioContext = new AudioContext({
   // Would be cool if I was wrong.
   latencyHint: 'playback',
 });
-
-// Doing it the way it's suggested in https://stackoverflow.com/a/39725071/10406353
-export const mediaElementSourcesMap: WeakMap<HTMLMediaElement, MediaElementAudioSourceNode> = new WeakMap();
-
-export function getOrCreateMediaElementSourceAndUpdateMap(element: HTMLMediaElement): MediaElementAudioSourceNode {
-  const srcFromMap = mediaElementSourcesMap.get(element);
-  let mediaElementSource: MediaElementAudioSourceNode;
-  if (srcFromMap) {
-    mediaElementSource = srcFromMap;
-    mediaElementSource.disconnect();
-  } else {
-    mediaElementSource = audioContext.createMediaElementSource(element);
-    mediaElementSourcesMap.set(element, mediaElementSource)
-  }
-  return mediaElementSource;
-}

src/entry-points/content/getOrCreateMediaElementSourceAndUpdateMap.ts

@@ -0,0 +1,50 @@
+/**
+ * @license
+ * Copyright (C) 2020, 2021, 2022, 2023  WofWca <[email protected]>
+ *
+ * This file is part of Jump Cutter Browser Extension.
+ *
+ * Jump Cutter Browser Extension is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Jump Cutter Browser Extension is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Jump Cutter Browser Extension.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+// Doing it the way it's suggested in https://stackoverflow.com/a/39725071/10406353
+export const mediaElementSourcesMap:
+  WeakMap<HTMLMediaElement, [AudioContext, MediaElementAudioSourceNode]>
+  = new WeakMap();
+
+/**
+ * @param getDefaultAudioContext must return an AudioContext that is gonna be used when
+ * `createMediaElementSource` has not been called for the `element` yet.
+ */
+export function getOrCreateMediaElementSourceAndUpdateMap(
+  element: HTMLMediaElement,
+  getDefaultAudioContext: () => AudioContext,
+): [AudioContext, MediaElementAudioSourceNode] {
+  const fromMap = mediaElementSourcesMap.get(element);
+  // let mediaElementSource: MediaElementAudioSourceNode;
+  if (fromMap) {
+    const mediaElementSource = fromMap[1];
+    // Act as if it's the first time that `createMediaElementSource` is called for the element
+    // (i.e. it's not connected to anything, not even `context.destination`).
+    mediaElementSource.disconnect();
+    return fromMap;
+  } else {
+    const audioContext = getDefaultAudioContext();
+    const mediaElementSource = audioContext.createMediaElementSource(element);
+    const tuple: [AudioContext, MediaElementAudioSourceNode]
+      = [audioContext, mediaElementSource];
+    mediaElementSourcesMap.set(element, tuple);
+    return tuple;
+  }
+}