allow to extract music bitrate info from formatInfo

MediaBrowser.MediaEncoding/Probing/ProbeResultNormalizer.cs

@@ -778,7 +778,11 @@ namespace MediaBrowser.MediaEncoding.Probing
                 }
             }
 
-            if (bitrate == 0 && formatInfo != null && !string.IsNullOrEmpty(formatInfo.BitRate) && stream.Type == MediaStreamType.Video)
+            // The bitrate info of FLAC musics and some videos is included in formatInfo.
+            if (bitrate == 0
+                && formatInfo != null
+                && !string.IsNullOrEmpty(formatInfo.BitRate)
+                && (stream.Type == MediaStreamType.Video || stream.Type == MediaStreamType.Audio))
             {
                 // If the stream info doesn't have a bitrate get the value from the media format info
                 if (int.TryParse(formatInfo.BitRate, NumberStyles.Any, _usCulture, out var value))