support audio sync transcoding

MediaBrowser.Controller/MediaEncoding/IMediaEncoder.cs

@@ -96,5 +96,16 @@ namespace MediaBrowser.Controller.MediaEncoding
         /// <param name="ticks">The ticks.</param>
         /// <returns>System.String.</returns>
         string GetTimeParameter(long ticks);
+
+        /// <summary>
+        /// Encodes the audio.
+        /// </summary>
+        /// <param name="options">The options.</param>
+        /// <param name="progress">The progress.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>Task.</returns>
+        Task<string> EncodeAudio(EncodingJobOptions options,
+            IProgress<double> progress,
+            CancellationToken cancellationToken);
     }
 }