Do not start loading on level update from interstitials-controller when autoStartLoad is false

Fix start on jagged audio/video segment boundaries before interstitial break

src/controller/buffer-controller.ts

@@ -810,15 +810,18 @@ transfer tracks: ${stringify(transferredTracks, (key, value) => (key === 'initSe
     const videoTrack = tracks.video;
     const videoSb = videoTrack?.buffer;
     if (videoSb && sn !== 'initSegment' && offset !== undefined) {
+      const audioSb = audioTrack?.buffer;
       const partOrFrag = part || (frag as MediaFragment);
       if (
         type === 'audio' &&
         parent !== 'main' &&
-        !(videoTrack.ending || videoTrack.ended)
+        !(videoTrack.ending || videoTrack.ended) &&
+        audioSb &&
+        BufferHelper.getBuffered(audioSb).length
       ) {
         const pStart = partOrFrag.start;
         const pTime = pStart + partOrFrag.duration * 0.05;
-        const vbuffered = videoSb.buffered;
+        const vbuffered = BufferHelper.getBuffered(videoSb);
         const vappending = this.currentOp('video');
         if (!vbuffered.length && !vappending) {
           // wait for video before appending audio

src/controller/interstitials-controller.ts

@@ -1031,7 +1031,8 @@ export default class InterstitialsController
   private checkStart() {
     const schedule = this.schedule;
     const interstitialEvents = schedule?.events;
-    if (!interstitialEvents || this.playbackDisabled || !this.media) {
+    const hls = this.hls;
+    if (!interstitialEvents || this.playbackDisabled || !this.media || !hls) {
       return;
     }
     // Check buffered to pre-roll
@@ -1042,7 +1043,11 @@ export default class InterstitialsController
     const timelinePos = this.timelinePos;
     const effectivePlayingItem = this.effectivePlayingItem;
     if (timelinePos === -1) {
-      const startPosition = this.hls.startPosition;
+      if (!hls.loadingEnabled) {
+        this.log(`waiting for startLoad( <startPosition> )`);
+        return;
+      }
+      const startPosition = hls.startPosition;
       this.timelinePos = startPosition;
       if (interstitialEvents.length === 0) {
         this.setSchedulePosition(0);
@@ -1056,7 +1061,7 @@ export default class InterstitialsController
           startPosition > 0 ? startPosition : 0);
         const index = schedule.findItemIndexAtTime(start);
         this.setSchedulePosition(index);
-      } else if (this.hls.liveSyncPosition === 0) {
+      } else if (hls.liveSyncPosition === 0) {
         this.setSchedulePosition(0);
       } else {
         this.log('[checkStart] waiting for live start');

tests/unit/controller/buffer-controller-operations.ts

@@ -1161,8 +1161,17 @@ describe('BufferController with attached media', function () {
 
     it('blocks audio append when video buffer is empty', function () {
       const audioQueue = getAudioQueue();
-      // Audio arrives with no video buffered - should be blocked
+      // Audio arrives with no video buffered - first append is not blocked
       triggerAudioAppend(0, 2);
+      // Queue should have block-audio op followed by the audio append
+      expect(audioQueue.length).to.equal(1);
+      expect(audioQueue[0].label).to.equal('append-audio');
+
+      audioQueue.length = 0;
+      setSourceBufferBufferedRange(bufferController, 'audio', 0, 2);
+
+      // Morem audio arrives with no video buffered - blocked
+      triggerAudioAppend(2, 4);
 
       // Queue should have block-audio op followed by the audio append
       expect(audioQueue.length).to.equal(2);
@@ -1185,6 +1194,7 @@ describe('BufferController with attached media', function () {
     it('blocks audio when audio is ahead of video', function () {
       // Video has buffered 0-5, but audio segment starts at 6 (ahead of video)
       setSourceBufferBufferedRange(bufferController, 'video', 0, 5);
+      setSourceBufferBufferedRange(bufferController, 'audio', 0, 6);
       (bufferController as any).lastVideoAppendEnd = 5;
 
       const audioQueue = getAudioQueue();
@@ -1197,8 +1207,9 @@ describe('BufferController with attached media', function () {
 
     it('unblocks audio when video append advances past blocked audio position', function () {
       const audioQueue = getAudioQueue();
-      // Audio arrives first, gets blocked (no video buffered)
-      triggerAudioAppend(0, 2);
+      // Audio arrives first, second append gets blocked (no video buffered)
+      setSourceBufferBufferedRange(bufferController, 'audio', 0, 1);
+      triggerAudioAppend(1, 1);
       expect(audioQueue[0].label).to.equal('block-audio');
 
       // Video append arrives — advances lastVideoAppendEnd past audio pTime
@@ -1234,11 +1245,11 @@ describe('BufferController with attached media', function () {
       )?.buffer;
       const audioQueue = getAudioQueue();
 
-      // First audio triggers block (no video buffered)
-      triggerAudioAppend(0, 2);
-      expect(audioQueue[0].label).to.equal('block-audio');
+      // First audio is appended
+      setSourceBufferBufferedRange(bufferController, 'audio', 0, 2);
 
-      // Second audio also triggers its own block (guard removed)
+      // Second audio also triggers block (guard removed)
+      triggerAudioAppend(2, 2);
       triggerAudioAppend(2, 2);
       expect(audioQueue.length).to.equal(4);
       expect(audioQueue[0].label).to.equal('block-audio');
@@ -1273,6 +1284,7 @@ describe('BufferController with attached media', function () {
       expect(audioQueue.length).to.equal(1);
       expect(audioQueue[0].label).to.equal('append-audio');
       expect(audioBuffer!.appendBuffer).to.have.been.calledOnce;
+      setSourceBufferBufferedRange(bufferController, 'audio', 0, 2);
 
       // While audio[0] is still in-flight (no updateend yet), second audio
       // arrives ahead of video — block-audio lands behind the in-flight append

tests/unit/controller/interstitials-controller.ts

@@ -167,6 +167,25 @@ describe('InterstitialsController', function () {
   }
 
   function setLoadedLevelDetails(playlist: string) {
+    const attrs = new AttrList({});
+    const level = new Level({
+      name: '',
+      url: '',
+      attrs,
+      bitrate: 0,
+    });
+
+    (hls.streamController as any).levels = [level];
+    (hls.levelController as any)._levels[0] = level;
+
+    // onManifestLoaded with autoStartLoaded kicks off loading
+    if (!hls.loadingEnabled) {
+      hls.startLoad(-1);
+    }
+
+    (hls.levelController as any).currentLevelIndex = 0;
+    (hls.levelController as any).currentLevel = level;
+
     const details = M3U8Parser.parseLevelPlaylist(
       playlist,
       'http://example.com/playlist.m3u8',
@@ -178,18 +197,9 @@ describe('InterstitialsController', function () {
     const timeSinceLoadedStub = sinon.stub(details, 'age');
     timeSinceLoadedStub.get(() => 0);
     expect(details.playlistParsingError).to.equal(null);
-    const attrs = new AttrList({});
-    const level = new Level({
-      name: '',
-      url: '',
-      attrs,
-      bitrate: 0,
-    });
+
     level.details = details;
-    (hls.streamController as any).levels = [level];
-    (hls.levelController as any)._levels[0] = level;
-    (hls.levelController as any).currentLevelIndex = 0;
-    (hls.levelController as any).currentLevel = level;
+
     hls.trigger(Events.LEVEL_LOADED, {
       details,
       levelInfo: level,
@@ -297,6 +307,7 @@ fileSequence4.ts
       const eventsTriggered = getTriggerCalls();
       expect(eventsTriggered).to.deep.equal(
         [
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1145,6 +1156,7 @@ fileSequence5.mp4`;
       const callsWithPrerollBeforeAttach = getTriggerCalls();
       expect(callsWithPrerollBeforeAttach).to.deep.equal(
         [
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1215,6 +1227,7 @@ fileSequence3.mp4
         [
           Events.MEDIA_ATTACHING,
           Events.MEDIA_ATTACHED,
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1283,6 +1296,7 @@ fileSequence3.mp4
         [
           Events.MEDIA_ATTACHING,
           Events.MEDIA_ATTACHED,
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1357,6 +1371,7 @@ fileSequence6.mp4`;
       const eventsBeforeAttach = getTriggerCalls();
       expect(eventsBeforeAttach).to.deep.equal(
         [
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1489,6 +1504,7 @@ fileSequence6.mp4`;
       const eventsAfterPlaylist = getTriggerCalls();
       expect(eventsAfterPlaylist).to.deep.equal(
         [
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -1820,6 +1836,7 @@ fileSequence6.mp4
       const eventsBeforeAttach = getTriggerCalls();
       expect(eventsBeforeAttach).to.deep.equal(
         [
+          Events.LEVEL_SWITCHING,
           Events.LEVEL_LOADED,
           Events.LEVEL_UPDATED,
           Events.INTERSTITIALS_UPDATED,
@@ -2139,6 +2156,7 @@ fileSequence3.mp4`;
       const expectedEvents = [
         Events.MEDIA_ATTACHING,
         Events.MEDIA_ATTACHED,
+        Events.LEVEL_SWITCHING,
         Events.LEVEL_LOADED,
         Events.LEVEL_UPDATED,
         Events.INTERSTITIALS_BUFFERED_TO_BOUNDARY,
@@ -2182,6 +2200,7 @@ media_w507366714_268.ts`;
       const expectedEvents = [
         Events.MEDIA_ATTACHING,
         Events.MEDIA_ATTACHED,
+        Events.LEVEL_SWITCHING,
         Events.LEVEL_LOADED,
         Events.LEVEL_UPDATED,
         Events.INTERSTITIALS_UPDATED,