fix vaapi pipeline with mpeg4 content (#51)

ErsatzTV.Core/FFmpeg/FFmpegComplexFilterBuilder.cs

@@ -14,6 +14,7 @@ namespace ErsatzTV.Core.FFmpeg
         private Option<TimeSpan> _audioDuration = None;
         private bool _deinterlace;
         private Option<HardwareAccelerationKind> _hardwareAccelerationKind = None;
+        private string _inputCodec;
         private Option<IDisplaySize> _padToSize = None;
         private Option<IDisplaySize> _scaleToSize = None;
 
@@ -47,6 +48,12 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
+        public FFmpegComplexFilterBuilder WithInputCodec(string codec)
+        {
+            _inputCodec = codec;
+            return this;
+        }
+
         public Option<FFmpegComplexFilter> Build()
         {
             var complexFilter = new StringBuilder();
@@ -55,6 +62,13 @@ namespace ErsatzTV.Core.FFmpeg
             var audioLabel = "0:a";
 
             HardwareAccelerationKind acceleration = _hardwareAccelerationKind.IfNone(HardwareAccelerationKind.None);
+            bool isHardwareDecode = acceleration switch
+            {
+                HardwareAccelerationKind.Vaapi => _inputCodec != "mpeg4",
+                HardwareAccelerationKind.Nvenc => true,
+                HardwareAccelerationKind.Qsv => true,
+                _ => false
+            };
 
             _audioDuration.IfSome(
                 audioDuration =>
@@ -67,6 +81,13 @@ namespace ErsatzTV.Core.FFmpeg
 
             var filterQueue = new List<string>();
 
+            bool usesHardwareFilters = acceleration != HardwareAccelerationKind.None && !isHardwareDecode &&
+                                       (_deinterlace || _scaleToSize.IsSome);
+            if (usesHardwareFilters)
+            {
+                filterQueue.Add("hwupload");
+            }
+
             if (_deinterlace)
             {
                 string filter = acceleration switch
@@ -102,7 +123,7 @@ namespace ErsatzTV.Core.FFmpeg
 
             if (_scaleToSize.IsSome || _padToSize.IsSome)
             {
-                if (acceleration != HardwareAccelerationKind.None)
+                if (acceleration != HardwareAccelerationKind.None && (isHardwareDecode || usesHardwareFilters))
                 {
                     filterQueue.Add("hwdownload");
                     string format = acceleration switch

ErsatzTV.Core/FFmpeg/FFmpegProcessBuilder.cs

@@ -153,6 +153,8 @@ namespace ErsatzTV.Core.FFmpeg
                 _arguments.Add(qsvCodec);
             }
 
+            _complexFilterBuilder = _complexFilterBuilder.WithInputCodec(codec);
+
             _arguments.Add("-i");
             _arguments.Add($"{input}");
             return this;