Support playback and audio track switching of audio-only stream with …

…main audio and alt audio

src/controller/buffer-controller.ts

@@ -141,12 +141,17 @@ class BufferController extends EventHandler {
     }
   }
 
-  onManifestParsed (data: { altAudio: boolean }) {
-    // in case of alt audio 2 BUFFER_CODECS events will be triggered, one per stream controller
+  onManifestParsed (data: { altAudio: boolean, audio: boolean, video: boolean }) {
+    // in case of alt audio (where all tracks have urls) 2 BUFFER_CODECS events will be triggered, one per stream controller
     // 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.bufferCodecEventsExpected = this._bufferCodecEventsTotal = data.altAudio ? 2 : 1;
+    let codecEvents: number = 2;
+    if (data.audio && !data.video || !data.altAudio) {
+      codecEvents = 1;
+    }
+    this.bufferCodecEventsExpected = this._bufferCodecEventsTotal = codecEvents;
+
     logger.log(`${this.bufferCodecEventsExpected} bufferCodec event(s) expected`);
   }
 

src/remux/mp4-remuxer.js

@@ -111,7 +111,7 @@ class MP4Remuxer {
       typeSupported = this.typeSupported,
       container = 'audio/mp4',
       tracks = {},
-      data = { tracks: tracks },
+      data = { tracks },
       computePTSDTS = (this._initPTS === undefined),
       initPTS, initDTS;
 
@@ -165,8 +165,11 @@ class MP4Remuxer {
       if (computePTSDTS) {
         initPTS = Math.min(initPTS, videoSamples[0].pts - inputTimeScale * timeOffset);
         initDTS = Math.min(initDTS, videoSamples[0].dts - inputTimeScale * timeOffset);
-        this.observer.trigger(Event.INIT_PTS_FOUND, { initPTS: initPTS });
+        this.observer.trigger(Event.INIT_PTS_FOUND, { initPTS });
       }
+    } else if (computePTSDTS && tracks.audio) {
+      // initPTS found for audio-only stream with main and alt audio
+      this.observer.trigger(Event.INIT_PTS_FOUND, { initPTS });
     }
 
     if (Object.keys(tracks).length) {

tests/unit/controller/buffer-controller.js

@@ -181,6 +181,11 @@ describe('BufferController tests', function () {
       expect(bufferController.bufferCodecEventsExpected).to.equal(2);
     });
 
+    it('expects one bufferCodec event if altAudio is signaled with audio only', function () {
+      bufferController.onManifestParsed({ altAudio: true, audio: true, video: false });
+      expect(bufferController.bufferCodecEventsExpected).to.equal(1);
+    });
+
     it('creates sourceBuffers when no more BUFFER_CODEC events are expected', function () {
       bufferController.pendingTracks = { video: {} };