Fixed: Media Info audio channel parsing of dual mono audio

Fixes #2182

src/NzbDrone.Core.Test/MediaFiles/MediaInfo/MediaInfoFormatterTests/FormatAudioChannelsFixture.cs

@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 using NUnit.Framework;
 using NzbDrone.Core.MediaFiles.MediaInfo;
 using NzbDrone.Test.Common;
@@ -131,5 +131,19 @@ namespace NzbDrone.Core.Test.MediaFiles.MediaInfo.MediaInfoFormatterTests
 
             MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(7.1m);
         }
+
+        [Test]
+        public void should_sum_dual_mono_representation_AudioChannelPositions()
+        {
+            var mediaInfoModel = new MediaInfoModel
+            {
+                AudioChannels = 2,
+                AudioChannelPositions = "1+1",
+                AudioChannelPositionsText = null,
+                SchemaRevision = 3
+            };
+
+            MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(2.0m);
+        }
     }
 }

src/NzbDrone.Core/MediaFiles/MediaInfo/MediaInfoFormatter.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Globalization;
 using System.IO;
 using System.Linq;
@@ -35,11 +35,17 @@ namespace NzbDrone.Core.MediaFiles.MediaInfo
                 return mediaInfo.AudioChannelPositionsText.ContainsIgnoreCase("LFE") ? audioChannels - 1 + 0.1m : audioChannels;
             }
 
+            if (audioChannelPositions.Contains("+"))
+            {
+                return audioChannelPositions.Split('+')
+                                            .Sum(s => decimal.Parse(s.Trim(), CultureInfo.InvariantCulture));
+            }
+
             return audioChannelPositions.Replace("Object Based / ", "")
-                                        .Split(new string[] { " / " }, StringSplitOptions.RemoveEmptyEntries)
-                                        .First()
-                                        .Split('/')
-                                        .Sum(s => decimal.Parse(s, CultureInfo.InvariantCulture));
+                                            .Split(new string[] { " / " }, StringSplitOptions.RemoveEmptyEntries)
+                                            .First()
+                                            .Split('/')
+                                            .Sum(s => decimal.Parse(s, CultureInfo.InvariantCulture));
         }
 
         public static string FormatAudioCodec(MediaInfoModel mediaInfo, string sceneName)