fix(HLS): Allow disable initial variant if necessary (#6940)

This change allows us to detect when the initial variant fails (for
example due to a 404, 503 in the m3u8 request) and we can change to
another variant.

lib/hls/hls_parser.js

@@ -2377,8 +2377,19 @@ shaka.hls.HlsParser = class {
 
       const uris = streamInfo.getUris();
       // Download the actual manifest.
-      const response = await this.requestManifest_(
-          streamInfo.getUris(), /* isPlaylist= */ true);
+      let response;
+      try {
+        response = await this.requestManifest_(
+            streamInfo.getUris(), /* isPlaylist= */ true);
+      } catch (e) {
+        stream.closeSegmentIndex();
+        const handled = this.playerInterface_.disableStream(stream);
+        if (handled) {
+          return;
+        } else {
+          throw e;
+        }
+      }
       if (abortSignal.aborted) {
         return;
       }

lib/player.js

@@ -2106,9 +2106,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
           });
         }
       },
-      disableStream: (stream) => {
-        this.disableStream(stream, this.config_.streaming.maxDisabledTime);
-      },
+      disableStream: (stream) => this.disableStream(
+          stream, this.config_.streaming.maxDisabledTime),
     };
     const regionTimeline =
         new shaka.media.RegionTimeline(() => this.seekRange());
@@ -2453,23 +2452,28 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     // Unless the user has already picked a variant, anyway, by calling
     // selectVariantTrack before this loading stage.
     let initialVariant = prefetchedVariant;
-    const activeVariant = this.streamingEngine_.getCurrentVariant();
-    if (!activeVariant && !initialVariant) {
-      initialVariant = this.chooseVariant_(/* initialSelection= */ true);
-      goog.asserts.assert(initialVariant, 'Must choose an initial variant!');
-    }
-
-    // Lazy-load the stream, so we will have enough info to make the playhead.
-    const createSegmentIndexPromises = [];
-    const toLazyLoad = activeVariant || initialVariant;
-    for (const stream of [toLazyLoad.video, toLazyLoad.audio]) {
-      if (stream && !stream.segmentIndex) {
-        createSegmentIndexPromises.push(stream.createSegmentIndex());
+    let toLazyLoad;
+    let activeVariant;
+    do {
+      activeVariant = this.streamingEngine_.getCurrentVariant();
+      if (!activeVariant && !initialVariant) {
+        initialVariant = this.chooseVariant_(/* initialSelection= */ true);
+        goog.asserts.assert(initialVariant, 'Must choose an initial variant!');
+      }
+
+      // Lazy-load the stream, so we will have enough info to make the playhead.
+      const createSegmentIndexPromises = [];
+      toLazyLoad = activeVariant || initialVariant;
+      for (const stream of [toLazyLoad.video, toLazyLoad.audio]) {
+        if (stream && !stream.segmentIndex) {
+          createSegmentIndexPromises.push(stream.createSegmentIndex());
+        }
       }
-    }
-    if (createSegmentIndexPromises.length > 0) {
-      await Promise.all(createSegmentIndexPromises);
-    }
+      if (createSegmentIndexPromises.length > 0) {
+        // eslint-disable-next-line no-await-in-loop
+        await Promise.all(createSegmentIndexPromises);
+      }
+    } while (!toLazyLoad || toLazyLoad.disabledUntilTime != 0);
 
     if (this.parser_ && this.parser_.onInitialVariantChosen) {
       this.parser_.onInitialVariantChosen(toLazyLoad);
@@ -6771,22 +6775,19 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       return str;
     };
 
+    let shouldStopTimer = true;
     for (const variant of this.manifest_.variants) {
       if (variant.disabledUntilTime > 0 && variant.disabledUntilTime <= now) {
         variant.disabledUntilTime = 0;
         hasVariantUpdate = true;
 
         shaka.log.v2('Re-enabled variant with ' + streamsAsString(variant));
       }
+      if (variant.disabledUntilTime > 0) {
+        shouldStopTimer = false;
+      }
     }
 
-    const shouldStopTimer = this.manifest_.variants.every((variant) => {
-      goog.asserts.assert(
-          variant.disabledUntilTime >= 0,
-          '|variant.disableTimeUntilTime| must always be >= 0');
-      return variant.disabledUntilTime === 0;
-    });
-
     if (shouldStopTimer) {
       this.checkVariantsTimer_.stop();
     }
@@ -7219,7 +7220,8 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     const hasAltStream = this.manifest_.variants.some((variant) => {
       const altStream = variant[stream.type];
 
-      if (altStream && altStream.id !== stream.id) {
+      if (altStream && altStream.id !== stream.id &&
+          !variant.disabledUntilTime) {
         if (shaka.util.StreamUtils.isAudio(stream)) {
           return stream.language === altStream.language;
         }