Merge pull request #5750 from iwalton3/fix-audio-selection-uns

Fix setting audio stream in PlaybackInfo for jellyfin-web.

(cherry picked from commit bf510ca04e2db84546286f696844ee2221e08efb)
Signed-off-by: Joshua M. Boniface <joshua@boniface.me>

Jellyfin.Api/Helpers/MediaInfoHelper.cs

@@ -282,6 +282,7 @@ namespace Jellyfin.Api.Helpers
                     if (streamInfo != null)
                     {
                         SetDeviceSpecificSubtitleInfo(streamInfo, mediaSource, auth.Token);
+                        mediaSource.DefaultAudioStreamIndex = streamInfo.AudioStreamIndex;
                     }
                 }
             }
@@ -326,6 +327,7 @@ namespace Jellyfin.Api.Helpers
                     if (streamInfo != null)
                     {
                         SetDeviceSpecificSubtitleInfo(streamInfo, mediaSource, auth.Token);
+                        mediaSource.DefaultAudioStreamIndex = streamInfo.AudioStreamIndex;
                     }
                 }
             }
@@ -353,6 +355,7 @@ namespace Jellyfin.Api.Helpers
 
                         // Do this after the above so that StartPositionTicks is set
                         SetDeviceSpecificSubtitleInfo(streamInfo, mediaSource, auth.Token);
+                        mediaSource.DefaultAudioStreamIndex = streamInfo.AudioStreamIndex;
                     }
                 }
                 else
@@ -390,6 +393,7 @@ namespace Jellyfin.Api.Helpers
 
                         // Do this after the above so that StartPositionTicks is set
                         SetDeviceSpecificSubtitleInfo(streamInfo, mediaSource, auth.Token);
+                        mediaSource.DefaultAudioStreamIndex = streamInfo.AudioStreamIndex;
                     }
                 }
             }