fix(live): only reset playlist loader for LLHLS (#1410)

videojs · Jul 25, 2023 · 0d8a7a3 · 0d8a7a3
1 parent 2079454
commit 0d8a7a3
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Showing 2 changed files with 52 additions and 8 deletions.
diff --git a/src/segment-loader.js b/src/segment-loader.js
@@ -1048,13 +1048,15 @@ export default class SegmentLoader extends videojs.EventTarget {
         // we must reset/resync the segment loader when we switch renditions and
         // the segment loader is already synced to the previous rendition
 
-        // on playlist changes we want it to be possible to fetch
-        // at the buffer for vod but not for live. So we use resetLoader
-        // for live and resyncLoader for vod. We want this because
-        // if a playlist uses independent and non-independent segments/parts the
-        // buffer may not accurately reflect the next segment that we should try
-        // downloading.
-        if (!newPlaylist.endList) {
+        // We only want to reset the loader here for LLHLS playback, as resetLoader sets fetchAtBuffer_
+        // to false, resulting in fetching segments at currentTime and causing repeated
+        // same-segment requests on playlist change. This erroneously drives up the playback watcher
+        // stalled segment count, as re-requesting segments at the currentTime or browser cached segments
+        // will not change the buffer.
+        // Reference for LLHLS fixes: https://github.com/videojs/http-streaming/pull/1201
+        const isLLHLS = !newPlaylist.endList && typeof newPlaylist.partTargetDuration === 'number';
+
+        if (isLLHLS) {
           this.resetLoader();
         } else {
           this.resyncLoader();

diff --git a/test/loader-common.js b/test/loader-common.js
@@ -865,7 +865,7 @@ export const LoaderCommonFactory = ({
       });
     });
 
-    QUnit.test('live rendition switch uses resetLoader', function(assert) {
+    QUnit.test('live LLHLS rendition switch uses resetLoader', function(assert) {
       return this.setupMediaSource(loader.mediaSource_, loader.sourceUpdater_).then(() => {
 
         loader.playlist(playlistWithDuration(50, {
@@ -896,6 +896,7 @@ export const LoaderCommonFactory = ({
         });
 
         newPlaylist.uri = 'playlist2.m3u8';
+        newPlaylist.partTargetDuration = 1;
 
         loader.playlist(newPlaylist);
 
@@ -906,6 +907,47 @@ export const LoaderCommonFactory = ({
       });
     });
 
+    QUnit.test('live rendition switch uses resyncLoader', function(assert) {
+      return this.setupMediaSource(loader.mediaSource_, loader.sourceUpdater_).then(() => {
+
+        loader.playlist(playlistWithDuration(50, {
+          mediaSequence: 0,
+          endList: false
+        }));
+
+        loader.load();
+        loader.mediaIndex = 0;
+        let resyncCalled = false;
+        let resetCalled = false;
+        const origReset = loader.resetLoader;
+        const origResync = loader.resyncLoader;
+
+        loader.resetLoader = function() {
+          resetCalled = true;
+          return origReset.call(loader);
+        };
+
+        loader.resyncLoader = function() {
+          resyncCalled = true;
+          return origResync.call(loader);
+        };
+
+        const newPlaylist = playlistWithDuration(50, {
+          mediaSequence: 0,
+          endList: false
+        });
+
+        newPlaylist.uri = 'playlist2.m3u8';
+
+        loader.playlist(newPlaylist);
+
+        assert.true(resyncCalled, 'resync was called');
+        assert.false(resetCalled, 'reset was not called');
+
+        return Promise.resolve();
+      });
+    });
+
     QUnit.test('vod rendition switch uses resyncLoader', function(assert) {
       return this.setupMediaSource(loader.mediaSource_, loader.sourceUpdater_).then(() => {