Merge pull request #872 from WillWill56/fix_sbnullref

Fix potential NullReferenceException

CONTRIBUTORS.md

@@ -18,6 +18,7 @@
  - [dkanada](https://github.com/dkanada)
  - [LogicalPhallacy](https://github.com/LogicalPhallacy/)
  - [RazeLighter777](https://github.com/RazeLighter777)
+ - [WillWill56](https://github.com/WillWill56)
 
 # Emby Contributors
 

MediaBrowser.Model/Dlna/StreamBuilder.cs

@@ -297,7 +297,7 @@ namespace MediaBrowser.Model.Dlna
             int? inputAudioChannels = audioStream?.Channels;
             int? inputAudioBitrate = audioStream?.BitDepth;
             int? inputAudioSampleRate = audioStream?.SampleRate;
-            int? inputAudioBitDepth = audioStream.BitDepth;
+            int? inputAudioBitDepth = audioStream?.BitDepth;
 
             if (directPlayMethods.Count() > 0)
             {