New: Preserve replaygain tags

src/NzbDrone.Core.Test/MediaFiles/AudioTagServiceFixture.cs

@@ -326,7 +326,7 @@ namespace NzbDrone.Core.Test.MediaFiles.AudioTagServiceFixture
         [Test]
         public void should_ignore_non_parsable_id3v23_date()
         {
-            GivenFileCopy("nin.mp2");
+            GivenFileCopy("nin.mp3");
 
             using (var file = TagLib.File.Create(_copiedFile))
             {
@@ -440,5 +440,37 @@ namespace NzbDrone.Core.Test.MediaFiles.AudioTagServiceFixture
             Mocker.GetMock<IEventAggregator>()
                 .Verify(v => v.PublishEvent(It.IsAny<TrackFileRetaggedEvent>()), Times.Once());
         }
+
+        [TestCase("nin.mp3")]
+        public void should_ignore_replaygain_tags_during_scrub(string filename)
+        {
+            Mocker.GetMock<IConfigService>()
+                .Setup(x => x.ScrubAudioTags)
+                .Returns(true);
+
+            GivenFileCopy(filename);
+
+            using (var preFile = TagLib.File.Create(_copiedFile))
+            {
+                preFile.Tag.ReplayGainAlbumPeak = 1;
+                preFile.Tag.ReplayGainAlbumGain = 500;
+                preFile.Tag.ReplayGainTrackPeak = 2;
+                preFile.Tag.ReplayGainTrackGain = 250;
+                preFile.Save();
+            }
+
+            var file = GivenPopulatedTrackfile(0);
+
+            file.Path = _copiedFile;
+            Subject.WriteTags(file, false, true);
+
+            using (var postFile = TagLib.File.Create(_copiedFile))
+            {
+                postFile.Tag.ReplayGainAlbumGain.Should().Be(500);
+                postFile.Tag.ReplayGainAlbumPeak.Should().Be(1);
+                postFile.Tag.ReplayGainTrackGain.Should().Be(250);
+                postFile.Tag.ReplayGainTrackPeak.Should().Be(2);
+            }
+        }
     }
 }

src/NzbDrone.Core/MediaFiles/AudioTagService.cs

@@ -151,8 +151,24 @@ namespace NzbDrone.Core.MediaFiles
             try
             {
                 file = TagLib.File.Create(path);
+
+                var replayGainAlbumGain = file.Tag.ReplayGainAlbumGain;
+                var replayGainAlbumPeak = file.Tag.ReplayGainAlbumPeak;
+                var replayGainTrackGain = file.Tag.ReplayGainTrackGain;
+                var replayGainTrackPeak = file.Tag.ReplayGainTrackPeak;
+
                 file.RemoveTags(TagLib.TagTypes.AllTags);
                 file.Save();
+                file.Dispose();
+
+                file = TagLib.File.Create(path);
+
+                file.Tag.ReplayGainAlbumGain = replayGainAlbumGain;
+                file.Tag.ReplayGainAlbumPeak = replayGainAlbumPeak;
+                file.Tag.ReplayGainTrackGain = replayGainTrackGain;
+                file.Tag.ReplayGainTrackPeak = replayGainTrackPeak;
+
+                file.Save();
             }
             catch (CorruptFileException ex)
             {