fix: audio track API for 1 track (#776)

reverts a bug fix in #759

it was a good patch but it prevented the audio tracks API to be
populated if there was just 1 audio track.
it's still expected that with 1 audio track, the API returns an item for
video.audioTracks[0].

this change adds that back in.

the root issue in hls.js I believe was that we were trying to select an
audio track with a string ID and hls.js works with numeric ID's.
this change also adds a check if hls.js audioTracks has the ID to which
the player tries to switch.

packages/playback-core/src/index.ts

@@ -536,6 +536,7 @@ export const loadMedia = (
     | 'subtitleTrack'
     | 'userConfig'
     | 'audioTrack'
+    | 'audioTracks'
     | 'autoLevelEnabled'
     | 'nextLevel'
     | 'levels'

packages/playback-core/src/media-tracks.ts

@@ -3,7 +3,10 @@ import type { VideoRenditionList } from 'media-tracks';
 
 export function setupMediaTracks(
   customMediaEl: HTMLMediaElement,
-  hls: Pick<Hls, 'audioTrack' | 'autoLevelEnabled' | 'nextLevel' | 'levels' | 'on' | 'once' | 'off' | 'trigger'>
+  hls: Pick<
+    Hls,
+    'audioTrack' | 'audioTracks' | 'autoLevelEnabled' | 'nextLevel' | 'levels' | 'on' | 'once' | 'off' | 'trigger'
+  >
 ) {
   if (!('videoTracks' in customMediaEl)) return;
 
@@ -36,9 +39,6 @@ export function setupMediaTracks(
   hls.on(Hls.Events.AUDIO_TRACKS_UPDATED, function (event, data) {
     removeAudioTracks();
 
-    // At least with ll-hls, there is a bug when enabling a single audio track (may be wider)
-    // for now, we can early bail if the `audioTracks` length is <=1. (CJP)
-    if (data.audioTracks.length <= 1) return;
     for (const a of data.audioTracks) {
       // hls.js doesn't return a `kind` property for audio tracks yet.
       const kind = a.default ? 'main' : 'alternative';
@@ -52,7 +52,12 @@ export function setupMediaTracks(
   });
 
   customMediaEl.audioTracks.addEventListener('change', () => {
-    hls.audioTrack = [...customMediaEl.audioTracks].find((t) => t.enabled).id;
+    // Cast to number, hls.js uses numeric id's.
+    const audioTrackId = +[...customMediaEl.audioTracks].find((t) => t.enabled)?.id;
+    const availableIds = hls.audioTracks.map((t) => t.id);
+    if (audioTrackId != hls.audioTrack && availableIds.includes(audioTrackId)) {
+      hls.audioTrack = audioTrackId;
+    }
   });
 
   // Fired when a level is removed after calling `removeLevel()`