1 files changed, 99 insertions, 0 deletions
diff --git a/MediaBrowser.Model/Dlna/ResolutionNormalizer.cs b/MediaBrowser.Model/Dlna/ResolutionNormalizer.cs
new file mode 100644
index 000000000..4fdf4972f
--- /dev/null
+++ b/MediaBrowser.Model/Dlna/ResolutionNormalizer.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using MediaBrowser.Model.Extensions;
+
+namespace MediaBrowser.Model.Dlna
+{
+    public class ResolutionNormalizer
+    {
+        private static readonly ResolutionConfiguration[] Configurations = 
+            new []
+            {
+                new ResolutionConfiguration(426, 320000),
+                new ResolutionConfiguration(640, 400000),
+                new ResolutionConfiguration(720, 950000),
+                new ResolutionConfiguration(1280, 2500000),
+                new ResolutionConfiguration(1920, 4000000),
+                new ResolutionConfiguration(3840, 35000000)
+            };
+
+        public static ResolutionOptions Normalize(int? inputBitrate,
+            int? unused1,
+            int? unused2,
+			int outputBitrate,
+			string inputCodec,
+            string outputCodec,
+            int? maxWidth,
+            int? maxHeight)
+        {
+			// If the bitrate isn't changing, then don't downlscale the resolution
+			if (inputBitrate.HasValue && outputBitrate >= inputBitrate.Value) 
+			{
+				if (maxWidth.HasValue || maxHeight.HasValue) 
+				{
+					return new ResolutionOptions
+					{
+						MaxWidth = maxWidth,
+						MaxHeight = maxHeight
+					};
+				}
+			}
+
+            var resolutionConfig = GetResolutionConfiguration(outputBitrate);
+            if (resolutionConfig != null)
+            {
+                var originvalValue = maxWidth;
+
+                maxWidth = Math.Min(resolutionConfig.MaxWidth, maxWidth ?? resolutionConfig.MaxWidth);
+                if (!originvalValue.HasValue || originvalValue.Value != maxWidth.Value)
+                {
+                    maxHeight = null;
+                }
+            }
+
+            return new ResolutionOptions
+            {
+                MaxWidth = maxWidth,
+                MaxHeight = maxHeight
+            };
+        }
+
+        private static ResolutionConfiguration GetResolutionConfiguration(int outputBitrate)
+        {
+            ResolutionConfiguration previousOption = null;
+
+            foreach (var config in Configurations)
+            {
+                if (outputBitrate <= config.MaxBitrate)
+                {
+                    return previousOption ?? config;
+                }
+
+                previousOption = config;
+            }
+
+            return null;
+        }
+
+        private static double GetVideoBitrateScaleFactor(string codec)
+        {
+            if (StringHelper.EqualsIgnoreCase(codec, "h265") ||
+                StringHelper.EqualsIgnoreCase(codec, "hevc") ||
+                StringHelper.EqualsIgnoreCase(codec, "vp9"))
+            {
+                return .5;
+            }
+            return 1;
+        }
+
+        public static int ScaleBitrate(int bitrate, string inputVideoCodec, string outputVideoCodec)
+        {
+            var inputScaleFactor = GetVideoBitrateScaleFactor(inputVideoCodec);
+            var outputScaleFactor = GetVideoBitrateScaleFactor(outputVideoCodec);
+            var scaleFactor = outputScaleFactor/inputScaleFactor;
+            var newBitrate = scaleFactor*bitrate;
+
+            return Convert.ToInt32(newBitrate);
+        }
+    }
+}