fix: stop alt loaders on main mediachanging to prevent append race (#895

)

src/master-playlist-controller.js

@@ -1346,9 +1346,6 @@ export class MasterPlaylistController extends videojs.EventTarget {
     if (usingAudioLoader && unsupportedAudio && this.media().attributes.AUDIO) {
       const audioGroup = this.media().attributes.AUDIO;
 
-      this.mediaTypes_.AUDIO.activePlaylistLoader.pause();
-      this.audioSegmentLoader_.pause();
-      this.audioSegmentLoader_.abort();
       this.master().playlists.forEach(variant => {
         const variantAudioGroup = variant.attributes && variant.attributes.AUDIO;
 

src/media-groups.js

@@ -105,6 +105,17 @@ export const onGroupChanged = (type, settings) => () => {
   startLoaders(activeGroup.playlistLoader, mediaType);
 };
 
+export const onGroupChanging = (type, settings) => () => {
+  const {
+    segmentLoaders: {
+      [type]: segmentLoader
+    }
+  } = settings;
+
+  segmentLoader.abort();
+  segmentLoader.pause();
+};
+
 /**
  * Returns a function to be called when the media track changes. It performs a
  * destructive reset of the SegmentLoader to ensure we start loading as close to
@@ -730,6 +741,7 @@ export const setupMediaGroups = (settings) => {
     mediaTypes[type].activeGroup = activeGroup(type, settings);
     mediaTypes[type].activeTrack = activeTrack[type](type, settings);
     mediaTypes[type].onGroupChanged = onGroupChanged(type, settings);
+    mediaTypes[type].onGroupChanging = onGroupChanging(type, settings);
     mediaTypes[type].onTrackChanged = onTrackChanged(type, settings);
   });
 
@@ -748,6 +760,10 @@ export const setupMediaGroups = (settings) => {
     ['AUDIO', 'SUBTITLES'].forEach(type => mediaTypes[type].onGroupChanged());
   });
 
+  masterPlaylistLoader.on('mediachanging', () => {
+    ['AUDIO', 'SUBTITLES'].forEach(type => mediaTypes[type].onGroupChanging());
+  });
+
   // custom audio track change event handler for usage event
   const onAudioTrackChanged = () => {
     mediaTypes.AUDIO.onTrackChanged();

test/media-groups.test.js

@@ -340,6 +340,32 @@ QUnit.test('activeGroup returns the correct subtitle group', function(assert) {
   );
 });
 
+QUnit.test('onGroupChanging aborts and pauses segment loaders', function(assert) {
+  const calls = {
+    abort: 0,
+    pause: 0
+  };
+  const segmentLoader = {
+    abort: () => calls.abort++,
+    pause: () => calls.pause++
+  };
+
+  const settings = {
+    segmentLoaders: {
+      AUDIO: segmentLoader
+    }
+  };
+  const type = 'AUDIO';
+
+  const onGroupChanging = MediaGroups.onGroupChanging(type, settings);
+
+  assert.deepEqual(calls, {abort: 0, pause: 0}, 'no calls yet');
+
+  onGroupChanging();
+
+  assert.deepEqual(calls, {abort: 1, pause: 1}, 'one abort one pause');
+});
+
 QUnit.test(
   'onGroupChanged updates active playlist loader and resyncs segment loader',
   function(assert) {