Fix/scheduling (Dash-Industry-Forum#4296)

* Fix bug in the request logic in case fastswitch is enabled. If there is no request that corresponds to a segment in the buffer to be replaced then perform a default quality switch.

* Do not check for a new quality in case we are already performing a default quality switch

package.json

@@ -1,6 +1,6 @@
 {
     "name": "dashjs",
-    "version": "4.7.2",
+    "version": "4.7.3",
     "description": "A reference client implementation for the playback of MPEG DASH via Javascript and compliant browsers.",
     "author": "Dash Industry Forum",
     "license": "BSD-3-Clause",

src/streaming/StreamProcessor.js

@@ -686,6 +686,7 @@ function StreamProcessor(config) {
         }, { mediaType: type, streamId: streamInfo.id });
 
         // Abort appending segments to the buffer. Also adjust the appendWindow as we might have been in the progress of prebuffering stuff.
+        scheduleController.setCheckPlaybackQuality(false);
         bufferController.prepareForForceReplacementQualitySwitch(representationInfo)
             .then(() => {
                 _bufferClearedForReplacement();
@@ -735,8 +736,7 @@ function StreamProcessor(config) {
                 _prepareForDefaultQualitySwitch(representationInfo);
             }
         } else {
-            scheduleController.startScheduleTimer();
-            qualityChangeInProgress = false;
+            _prepareForDefaultQualitySwitch(representationInfo);
         }
     }
 
@@ -752,6 +752,7 @@ function StreamProcessor(config) {
 
         bufferController.updateBufferTimestampOffset(representationInfo)
             .then(() => {
+                scheduleController.setCheckPlaybackQuality(false);
                 if (mediaInfo.segmentAlignment || mediaInfo.subSegmentAlignment) {
                     scheduleController.startScheduleTimer();
                 } else {