fix: calling detatchMedia() followed by attachMedia() causes audio to…

… not play

On re-attch the context of altAudio is not saved in buffer control so it doesn't know to create two source buffers.
Also, in context of stream controller it doesn't reset the `altAudio` flag.
I also noticed that stream controller is reloading the entire frags it has in `fragmentTracker` and it seems it needs to be reset on detach, otherwise there's a very long start delay where unncessery buffering occurs.

based on #2110 and fixes #2099.

src/controller/buffer-controller.ts

@@ -47,6 +47,9 @@ class BufferController extends EventHandler {
   // signals that mediaSource should have endOfStream called
   private _needsEos: boolean = false;
 
+  // Track whether the parsed manifest signaled alternate audio
+  // private _altAudio: boolean = false;
+
   private config: BufferControllerConfig;
 
   // this is optional because this property is removed from the class sometimes
@@ -143,6 +146,7 @@ class BufferController extends EventHandler {
     // sourcebuffers will be created all at once when the expected nb of tracks will be reached
     // in case alt audio is not used, only one BUFFER_CODEC event will be fired from main stream controller
     // it will contain the expected nb of source buffers, no need to compute it
+    // this._altAudio = data.altAudio;
     this.bufferCodecEventsExpected = data.altAudio ? 2 : 1;
     logger.log(`${this.bufferCodecEventsExpected} bufferCodec event(s) expected`);
   }
@@ -202,6 +206,7 @@ class BufferController extends EventHandler {
       this.mediaSource = null;
       this.media = null;
       this._objectUrl = null;
+      // this.bufferCodecEventsExpected = this._altAudio ? 2 : 1;
       this.pendingTracks = {};
       this.tracks = {};
       this.sourceBuffer = {};

src/controller/stream-controller.js

@@ -691,7 +691,8 @@ class StreamController extends BaseStreamController {
       media.removeEventListener('ended', this.onvended);
       this.onvseeking = this.onvseeked = this.onvended = null;
     }
-    this.media = this.mediaBuffer = null;
+    this.fragmentTracker.removeAllFragments();
+    this.media = this.mediaBuffer = this.altAudio = null;
     this.loadedmetadata = false;
     this.stopLoad();
   }