fix: Fix HLS dynamic to static transition (#4483)

fix: Fix HLS dynamic to static transition

 - Keep maxSegmentEndTime_ updated in PresentationTimeline by calling
   notifySegments on each HLS playlist update, so that the seek range
   doesn't revert to the original playlist size when it becomes
   static.
 - Wait to change the presentation type to VOD until after _all_
   active playlists have an ENDLIST tag, to avoid missing the final
   segments in one type or the other.
 - Stop updating the playlists after transition to VOD.
 - Update the MSE duration at exactly the same time as we transition
   to VOD, to avoid a loophole where the UI knows it's VOD, but
   doesn't have any way to get the correct duration.  Previously, this
   state would persist until the final segments were appended.

Closes #4431

externs/shaka/manifest_parser.js

@@ -111,7 +111,8 @@ shaka.extern.ManifestParser = class {
  *   onError: function(!shaka.util.Error),
  *   isLowLatencyMode: function():boolean,
  *   isAutoLowLatencyMode: function():boolean,
- *   enableLowLatencyMode: function()
+ *   enableLowLatencyMode: function(),
+ *   updateDuration: function()
  * }}
  *
  * @description
@@ -147,6 +148,8 @@ shaka.extern.ManifestParser = class {
  *   Return true if auto low latency streaming mode is enabled.
  * @property {function()} enableLowLatencyMode
  *   Enable low latency streaming mode.
+ * @property {function()} updateDuration
+ *   Update the presentation duration based on PresentationTimeline.
  * @exportDoc
  */
 shaka.extern.ManifestParser.PlayerInterface;

lib/hls/hls_parser.js

@@ -287,6 +287,21 @@ shaka.hls.HlsParser = class {
     }
 
     await Promise.all(updates);
+
+    this.notifySegments_();
+
+    // If any hasEndList is false, the stream is still live.
+    const stillLive = streamInfos.some((s) => s.hasEndList == false);
+    if (!stillLive) {
+      // Convert the presentation to VOD and set the duration.
+      const PresentationType = shaka.hls.HlsParser.PresentationType_;
+      this.setPresentationType_(PresentationType.VOD);
+
+      const maxTimestamps = streamInfos.map((s) => s.maxTimestamp);
+      // The duration is the minimum of the end times of all streams.
+      this.presentationTimeline_.setDuration(Math.min(...maxTimestamps));
+      this.playerInterface_.updateDuration();
+    }
   }
 
   /**
@@ -297,7 +312,6 @@ shaka.hls.HlsParser = class {
    * @private
    */
   async updateStream_(streamInfo) {
-    const PresentationType = shaka.hls.HlsParser.PresentationType_;
     const manifestUri = streamInfo.absoluteMediaPlaylistUri;
     const uriObj = new goog.Uri(manifestUri);
     if (this.lowLatencyMode_ && streamInfo.canSkipSegments) {
@@ -330,6 +344,7 @@ shaka.hls.HlsParser = class {
         streamInfo.verbatimMediaPlaylistUri, playlist, stream.type,
         stream.mimeType, streamInfo.mediaSequenceToStartTime, mediaVariables,
         stream.codecs);
+    this.segmentsToNotifyByStream_.push(segments);
 
     stream.segmentIndex.mergeAndEvict(
         segments, this.presentationTimeline_.getSegmentAvailabilityStart());
@@ -350,10 +365,10 @@ shaka.hls.HlsParser = class {
         shaka.hls.Utils.getFirstTagWithName(playlist.tags, 'EXT-X-ENDLIST');
 
     if (endListTag) {
-      // Convert the presentation to VOD and set the duration to the last
-      // segment's end time.
-      this.setPresentationType_(PresentationType.VOD);
-      this.presentationTimeline_.setDuration(newestSegment.endTime);
+      // Flag this for later.  We don't convert the whole presentation into VOD
+      // until we've seen the ENDLIST tag for all active playlists.
+      streamInfo.hasEndList = true;
+      streamInfo.maxTimestamp = newestSegment.endTime;
     }
   }
 
@@ -1761,6 +1776,7 @@ shaka.hls.HlsParser = class {
       maxTimestamp: lastEndTime,
       mediaSequenceToStartTime,
       canSkipSegments,
+      hasEndList: false,
     };
   }
 
@@ -2523,8 +2539,11 @@ shaka.hls.HlsParser = class {
     try {
       await this.update();
 
-      const delay = this.updatePlaylistDelay_;
-      this.updatePlaylistTimer_.tickAfter(/* seconds= */ delay);
+      // This may have converted to VOD, in which case we stop updating.
+      if (this.isLive_()) {
+        const delay = this.updatePlaylistDelay_;
+        this.updatePlaylistTimer_.tickAfter(/* seconds= */ delay);
+      }
     } catch (error) {
       // Detect a call to stop() during this.update()
       if (!this.playerInterface_) {
@@ -2707,7 +2726,8 @@ shaka.hls.HlsParser = class {
  *   absoluteMediaPlaylistUri: string,
  *   maxTimestamp: number,
  *   mediaSequenceToStartTime: !Map.<number, number>,
- *   canSkipSegments: boolean
+ *   canSkipSegments: boolean,
+ *   hasEndList: boolean
  * }}
  *
  * @description
@@ -2730,6 +2750,8 @@ shaka.hls.HlsParser = class {
  * @property {boolean} canSkipSegments
  *  True if the server supports delta playlist updates, and we can send a
  *  request for a playlist that can skip older media segments.
+ * @property {boolean} hasEndList
+ *  True if the stream has an EXT-X-ENDLIST tag.
  */
 shaka.hls.HlsParser.StreamInfo;
 

lib/media/media_source_engine.js

@@ -849,21 +849,25 @@ shaka.media.MediaSourceEngine = class {
   }
 
   /**
-   * We only support increasing duration at this time.  Decreasing duration
-   * causes the MSE removal algorithm to run, which results in an 'updateend'
-   * event.  Supporting this scenario would be complicated, and is not currently
-   * needed.
-   *
    * @param {number} duration
    * @return {!Promise}
    */
   async setDuration(duration) {
-    goog.asserts.assert(
-        isNaN(this.mediaSource_.duration) ||
-            this.mediaSource_.duration <= duration,
-        'duration cannot decrease: ' + this.mediaSource_.duration + ' -> ' +
-            duration);
     await this.enqueueBlockingOperation_(() => {
+      // Reducing the duration causes the MSE removal algorithm to run, which
+      // triggers an 'updateend' event to fire.  To handle this scenario, we
+      // have to insert a dummy operation into the beginning of each queue,
+      // which the 'updateend' handler will remove.
+      if (duration < this.mediaSource_.duration) {
+        for (const contentType in this.sourceBuffers_) {
+          const dummyOperation = {
+            start: () => {},
+            p: new shaka.util.PublicPromise(),
+          };
+          this.queues_[contentType].unshift(dummyOperation);
+        }
+      }
+
       this.mediaSource_.duration = duration;
     });
   }

lib/media/streaming_engine.js

@@ -774,7 +774,7 @@ shaka.media.StreamingEngine = class {
         this.manifest_.sequenceMode);
     this.destroyer_.ensureNotDestroyed();
 
-    this.setDuration_();
+    this.updateDuration();
 
     for (const type of streamsByType.keys()) {
       const stream = streamsByType.get(type);
@@ -824,9 +824,8 @@ shaka.media.StreamingEngine = class {
 
   /**
    * Sets the MediaSource's duration.
-   * @private
    */
-  setDuration_() {
+  updateDuration() {
     const duration = this.manifest_.presentationTimeline.getDuration();
     if (duration < Infinity) {
       this.playerInterface_.mediaSourceEngine.setDuration(duration);

lib/offline/storage.js

@@ -1169,6 +1169,7 @@ shaka.offline.Storage = class {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
 
     parser.configure(config.manifest);

lib/player.js

@@ -1770,6 +1770,11 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       enableLowLatencyMode: () => {
         this.configure('streaming.lowLatencyMode', true);
       },
+      updateDuration: () => {
+        if (this.streamingEngine_) {
+          this.streamingEngine_.updateDuration();
+        }
+      },
     };
 
     const startTime = Date.now() / 1000;

test/dash/dash_parser_content_protection_unit.js

@@ -43,6 +43,7 @@ describe('DashParser ContentProtection', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
 
     const actual = await dashParser.start(

test/dash/dash_parser_live_unit.js

@@ -36,6 +36,7 @@ describe('DashParser Live', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
   });
 

test/dash/dash_parser_manifest_unit.js

@@ -52,6 +52,7 @@ describe('DashParser Manifest', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
   });
 

test/dash/dash_parser_segment_base_unit.js

@@ -38,6 +38,7 @@ describe('DashParser SegmentBase', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
   });
 

test/dash/dash_parser_segment_list_unit.js

@@ -348,6 +348,7 @@ describe('DashParser SegmentList', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
     const manifest = await dashParser.start('dummy://foo', playerInterface);
     const stream = manifest.variants[0].video;

test/dash/dash_parser_segment_template_unit.js

@@ -47,6 +47,7 @@ describe('DashParser SegmentTemplate', () => {
       isLowLatencyMode: () => false,
       isAutoLowLatencyMode: () => false,
       enableLowLatencyMode: () => {},
+      updateDuration: () => {},
     };
   });