Added a entropy-calculating filter.

skyscraper8/Skyscraper/Math/EntropyCalculatorStream.cs

@@ -57,6 +57,8 @@ namespace skyscraper8.Skyscraper.Math
 			}
 
 			//Raise events if we feel like it
+			if (EntropyRising != null || EntropyFalling != null)
+			{
 				if (newEntropy != Entropy)
 				{
 					double oldEntropy = Entropy;
@@ -67,6 +69,7 @@ namespace skyscraper8.Skyscraper.Math
 					else if (newEntropy < Entropy)
 						EntropyFalling?.Invoke(oldEntropy, newEntropy, oldPercentage, newPercentage);
 				}
+			}
 
 			_entropy = newEntropy;
 		}

skyscraper8/Skyscraper/Math/PidEntryCalculatorFilter.cs

@@ -0,0 +1,45 @@
+using skyscraper5.Mpeg2;
+using skyscraper5.src.Mpeg2.PacketFilter;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace skyscraper8.Skyscraper.Math
+{
+    public class PidEntryCalculatorFilter : IPacketFilter
+    {
+        public bool PassPacket(TsPacket packet)
+        {
+            if (entropyCalculatorStreams == null)
+                entropyCalculatorStreams = new EntropyCalculatorStream[0x1fff];
+
+            if (packet.PayloadFlagSet)
+            {
+                uint pid = packet.PID;
+                if (entropyCalculatorStreams[pid] == null)
+                    entropyCalculatorStreams[pid] = new EntropyCalculatorStream();
+                entropyCalculatorStreams[pid].Write(packet.Payload);
+            }
+            return true;
+        }
+
+        private EntropyCalculatorStream[] entropyCalculatorStreams;
+
+        public double GetEntropy(int pid)
+        {
+            if (pid < 0)
+                throw new ArgumentOutOfRangeException(nameof(pid));
+
+            if (pid > entropyCalculatorStreams.Length)
+                throw new ArgumentOutOfRangeException(nameof(pid));
+
+            EntropyCalculatorStream stream = entropyCalculatorStreams[pid];
+            if (stream == null)
+                return double.NaN;
+
+            return stream.Entropy;
+        }
+    }
+}