added dual pass image extraction

MediaBrowser.Server.Implementations/HttpServer/HttpServer.cs

@@ -357,10 +357,7 @@ namespace MediaBrowser.Server.Implementations.HttpServer
                 _logger.ErrorException("AcceptWebSocketAsync error", ex);
 
                 ctx.Response.StatusCode = 500;
-            }
-            finally
-            { 
-                ctx.Response.Close(); 
+                ctx.Response.Close();
             }
         }
 

MediaBrowser.Server.Implementations/MediaEncoder/MediaEncoder.cs

@@ -708,11 +708,26 @@ namespace MediaBrowser.Server.Implementations.MediaEncoder
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
         /// <exception cref="System.ArgumentException">Must use inputPath list overload</exception>
-        public Task ExtractImage(string[] inputFiles, InputType type, TimeSpan? offset, string outputPath, CancellationToken cancellationToken)
+        public async Task ExtractImage(string[] inputFiles, InputType type, TimeSpan? offset, string outputPath, CancellationToken cancellationToken)
         {
             var resourcePool = type == InputType.AudioFile ? _audioImageResourcePool : _videoImageResourcePool;
 
-            return ExtractImageInternal(GetInputArgument(inputFiles, type), type, offset, outputPath, resourcePool, cancellationToken);
+            var inputArgument = GetInputArgument(inputFiles, type);
+
+            if (type != InputType.AudioFile)
+            {
+                try
+                {
+                    await ExtractImageInternal(inputArgument, type, offset, outputPath, true, resourcePool, cancellationToken).ConfigureAwait(false);
+                    return;
+                }
+                catch
+                {
+                    _logger.Error("I-frame image extraction failed, will attempt standard way. Input: {0}", inputArgument);
+                }
+            }
+
+            await ExtractImageInternal(inputArgument, type, offset, outputPath, false, resourcePool, cancellationToken).ConfigureAwait(false);
         }
 
         /// <summary>
@@ -722,6 +737,7 @@ namespace MediaBrowser.Server.Implementations.MediaEncoder
         /// <param name="type">The type.</param>
         /// <param name="offset">The offset.</param>
         /// <param name="outputPath">The output path.</param>
+        /// <param name="useIFrame">if set to <c>true</c> [use I frame].</param>
         /// <param name="resourcePool">The resource pool.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
@@ -729,7 +745,7 @@ namespace MediaBrowser.Server.Implementations.MediaEncoder
         /// or
         /// outputPath</exception>
         /// <exception cref="System.ApplicationException"></exception>
-        private async Task ExtractImageInternal(string inputPath, InputType type, TimeSpan? offset, string outputPath, SemaphoreSlim resourcePool, CancellationToken cancellationToken)
+        private async Task ExtractImageInternal(string inputPath, InputType type, TimeSpan? offset, string outputPath, bool useIFrame, SemaphoreSlim resourcePool, CancellationToken cancellationToken)
         {
             if (string.IsNullOrEmpty(inputPath))
             {
@@ -741,7 +757,7 @@ namespace MediaBrowser.Server.Implementations.MediaEncoder
                 throw new ArgumentNullException("outputPath");
             }
 
-            var args = type != InputType.Dvd ? string.Format("-i {0} -threads 0 -v quiet -vframes 1 -filter:v select=\\'eq(pict_type\\,I)\\' -f image2 \"{1}\"", inputPath, outputPath) :
+            var args = useIFrame ? string.Format("-i {0} -threads 0 -v quiet -vframes 1 -filter:v select=\\'eq(pict_type\\,I)\\' -f image2 \"{1}\"", inputPath, outputPath) :
                 string.Format("-i {0} -threads 0 -v quiet -vframes 1 -f image2 \"{1}\"", inputPath, outputPath);
 
             var probeSize = GetProbeSizeArgument(type);