Add comments.

lib/components/PlayerScreen/feature_chips.dart

@@ -40,6 +40,10 @@ class FeatureState {
       ? null
       : metadata?.mediaSourceInfo.mediaStreams
           .firstWhereOrNull((stream) => stream.type == "Audio");
+  // Transcoded downloads will not have a valid MediaStream, but will have
+  // the target transcode bitrate set for the mediasource bitrate.  Other items
+  // should have a valid mediaStream, so use that audio-only bitrate instead of the
+  // whole-file bitrate.
   int? get bitrate => isTranscoding
       ? settings.transcodeBitrate
       : audioStream?.bitRate ?? metadata?.mediaSourceInfo.bitrate;

lib/services/metadata_provider.dart

@@ -40,6 +40,9 @@ class MetadataRequest {
       item.id, queueItem?.id, includeLyrics, checkIfSpeedControlNeeded);
 }
 
+/// A storage container for metadata about a song.  The codec information will reflect
+/// the downloaded file if appropriate, even for transcoded downloads.  Online
+/// transcoding will not be reflected.
 class MetadataProvider {
   static const speedControlGenres = ["audiobook", "podcast", "speech"];
   static const speedControlLongTrackDuration = Duration(minutes: 15);
@@ -93,6 +96,8 @@ final AutoDisposeFutureProviderFamily<MetadataProvider?, MetadataRequest>
           ? profile?.stereoBitrate
           : downloadItem.baseItem!.mediaSources?.first.bitrate;
 
+      // We cannot create a fully accurate MediaStream for a transcoded item, so
+      // just return an empty list.
       List<MediaStream> mediaStream =
           profile?.codec != FinampTranscodingCodec.original
               ? []