preserve image with audio sync encoding

MediaBrowser.MediaEncoding/Encoder/AudioEncoder.cs

@@ -41,19 +41,36 @@ namespace MediaBrowser.MediaEncoding.Encoder
                 }
             }
 
-            const string vn = " -vn";
-
             var threads = GetNumberOfThreads(state, false);
 
             var inputModifier = GetInputModifier(state);
 
-            return string.Format("{0} {1} -threads {2}{3} {4} -id3v2_version 3 -write_id3v1 1 -y \"{5}\"",
+            var albumCoverInput = string.Empty;
+            var mapArgs = string.Empty;
+            var metadata = string.Empty;
+            var vn = string.Empty;
+
+            if (!string.IsNullOrWhiteSpace(state.AlbumCoverPath))
+            {
+                albumCoverInput = " -i \"" + state.AlbumCoverPath + "\"";
+                mapArgs = " -map 0:a -map 1:v -c:v copy";
+                metadata = " -metadata:s:v title=\"Album cover\" -metadata:s:v comment=\"Cover(Front)\"";
+            }
+            else
+            {
+                vn = " -vn";
+            }
+
+            return string.Format("{0} {1}{6}{7} -threads {2}{3} {4} -id3v2_version 3 -write_id3v1 1{8} -y \"{5}\"",
                 inputModifier,
                 GetInputArgument(state),
                 threads,
                 vn,
                 string.Join(" ", audioTranscodeParams.ToArray()),
-                state.OutputFilePath).Trim();
+                state.OutputFilePath,
+                albumCoverInput,
+                mapArgs,
+                metadata).Trim();
         }
 
         protected override string GetOutputFileExtension(EncodingJob state)

MediaBrowser.MediaEncoding/Encoder/EncodingJob.cs

@@ -64,6 +64,7 @@ namespace MediaBrowser.MediaEncoding.Encoder
         public long? InputFileSize { get; set; }
         public string OutputAudioSync = "1";
         public string OutputVideoSync = "vfr";
+        public string AlbumCoverPath { get; set; }
 
         public string GetMimeType(string outputPath)
         {

MediaBrowser.MediaEncoding/Encoder/EncodingJobFactory.cs

@@ -60,6 +60,14 @@ namespace MediaBrowser.MediaEncoding.Encoder
 
             state.IsInputVideo = string.Equals(item.MediaType, MediaType.Video, StringComparison.OrdinalIgnoreCase);
 
+            var primaryImage = item.GetImageInfo(ImageType.Primary, 0) ??
+                               item.Parents.Select(i => i.GetImageInfo(ImageType.Primary, 0)).FirstOrDefault(i => i != null);
+
+            if (primaryImage != null)
+            {
+                state.AlbumCoverPath = primaryImage.Path;
+            }
+
             var mediaSources = await _mediaSourceManager.GetPlayackMediaSources(request.ItemId, null, false, new[] { MediaType.Audio, MediaType.Video }, cancellationToken).ConfigureAwait(false);
 
             var mediaSource = string.IsNullOrEmpty(request.MediaSourceId)