Fixed: FLAC audio channels in media info

(cherry picked from commit ab45910e5643aa8390797ae98af94eac690b3bb5)

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

@@ -64,6 +64,21 @@ namespace NzbDrone.Core.Test.MediaFiles.MediaInfo.MediaInfoFormatterTests
             MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(2);
         }
 
+        [Test]
+        public void should_use_AudioChannels_if_schema_revision_is_3_and_AudioChannelPositions_is_0()
+        {
+            var mediaInfoModel = new MediaInfoModel
+            {
+                AudioFormat = "FLAC",
+                AudioChannelsContainer = 6,
+                AudioChannelPositions = "0/0/0",
+                AudioChannelPositionsTextContainer = null,
+                SchemaRevision = 3
+            };
+
+            MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(5.1m);
+        }
+
         [Test]
         public void should_sum_AudioChannelPositions()
         {
@@ -128,6 +143,21 @@ namespace NzbDrone.Core.Test.MediaFiles.MediaInfo.MediaInfoFormatterTests
             MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(7.1m);
         }
 
+        [Test]
+        public void should_format_6_channel_zero_as_51_if_flac()
+        {
+            var mediaInfoModel = new MediaInfoModel
+            {
+                AudioFormat = "FLAC",
+                AudioChannelsContainer = 6,
+                AudioChannelPositions = "0/0/0",
+                AudioChannelPositionsTextContainer = null,
+                SchemaRevision = 3
+            };
+
+            MediaInfoFormatter.FormatAudioChannels(mediaInfoModel).Should().Be(5.1m);
+        }
+
         [Test]
         public void should_ignore_culture_on_channel_summary()
         {

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

@@ -21,12 +21,12 @@ namespace NzbDrone.Core.MediaFiles.MediaInfo
         {
             var audioChannels = FormatAudioChannelsFromAudioChannelPositions(mediaInfo);
 
-            if (audioChannels == null)
+            if (audioChannels == null || audioChannels == 0.0m)
             {
                 audioChannels = FormatAudioChannelsFromAudioChannelPositionsText(mediaInfo);
             }
 
-            if (audioChannels == null)
+            if (audioChannels == null || audioChannels == 0.0m)
             {
                 audioChannels = FormatAudioChannelsFromAudioChannels(mediaInfo);
             }
@@ -565,6 +565,12 @@ namespace NzbDrone.Core.MediaFiles.MediaInfo
                 return audioChannelsContainer - 1 + 0.1m;
             }
 
+            // FLAC 6 channels is likely 5.1
+            if (audioFormat.ContainsIgnoreCase("FLAC") && audioChannelsContainer == 6)
+            {
+                return 5.1m;
+            }
+
             if (mediaInfo.SchemaRevision > 5)
             {
                 return audioChannelsStream > 0 ? audioChannelsStream : audioChannelsContainer;