Add fade in/out function.

src/SoundMaker/Sounds/SoundChannels/PseudoTriangleSoundChannel.cs

@@ -32,7 +32,9 @@ public override ushort[] GenerateWave()
         var result = new List<ushort>();
         foreach (var soundComponent in SoundComponents)
         {
-            result.AddRange(soundComponent.GenerateWave(Format, Tempo, new PseudoTriangleWave()));
+            var wave = soundComponent.GenerateWave(Format, Tempo, new PseudoTriangleWave());
+            FadeInOut(wave);
+            result.AddRange(wave);
         }
         return result.ToArray();
     }

src/SoundMaker/Sounds/SoundChannels/SoundChannelBase.cs

@@ -119,6 +119,20 @@ public void Import(IEnumerable<ISoundComponent> components)
 
     public abstract ushort[] GenerateWave();
 
+    protected void FadeInOut(ushort[] wave)
+    {
+        var tenMSCount = (int)((double)Format.SamplingFrequency * 0.01);
+        if (wave.Length > tenMSCount << 1)
+        {
+            for (int i = 0; i < tenMSCount; i++)
+            {
+                double magnification = (1.0 / tenMSCount) * (i + 1);
+                wave[i] = (ushort)(((short)(wave[i] - short.MaxValue - 1) * magnification) + short.MaxValue + 1);
+                wave[wave.Length - i - 1] = (ushort)(((short)(wave[wave.Length - i - 1] - short.MaxValue - 1) * magnification) + short.MaxValue + 1);
+            }
+        }
+    }
+
     public IEnumerator<ISoundComponent> GetEnumerator()
     {
         return SoundComponents.GetEnumerator();

src/SoundMaker/Sounds/SoundChannels/SquareSoundChannel.cs

@@ -45,7 +45,8 @@ public override ushort[] GenerateWave()
         var result = new List<ushort>();
         foreach (var soundComponent in SoundComponents)
         {
-            result.AddRange(soundComponent.GenerateWave(Format, Tempo, new SquareWave(Ratio)));
+            var wave = soundComponent.GenerateWave(Format, Tempo, new SquareWave(Ratio));
+            result.AddRange(wave);
         }
         return result.ToArray();
     }

src/SoundMaker/Sounds/SoundChannels/TriangleSoundChannel.cs

@@ -31,7 +31,9 @@ public override ushort[] GenerateWave()
         var result = new List<ushort>();
         foreach (var soundComponent in SoundComponents)
         {
-            result.AddRange(soundComponent.GenerateWave(Format, Tempo, new TriangleWave()));
+            var wave = soundComponent.GenerateWave(Format, Tempo, new TriangleWave());
+            FadeInOut(wave);
+            result.AddRange(wave);
         }
         return result.ToArray();
     }