rearrange the api of DCFilter a bit to make it less dumb. nothing of real importance

BizHawk.Emulation/Consoles/Atari/2600/Atari2600.Core.cs

@@ -185,7 +185,7 @@ namespace BizHawk
 			//tia = new TIA(this, frameBuffer);
 			tia = new TIA(this);
 			// dcfilter coefficent is from real observed hardware behavior: a latched "1" will fully decay by ~170 or so tia sound cycles
-			dcfilter = new Emulation.Sound.Utilities.DCFilter(tia, 256);
+			dcfilter = Emulation.Sound.Utilities.DCFilter.AsISoundProvider(tia, 256);
 			// Setup 6532
 			m6532 = new M6532(this);
 

BizHawk.Emulation/Consoles/Nintendo/Gameboy/Gambatte.cs

@@ -738,7 +738,7 @@ namespace BizHawk.Emulation.Consoles.GB
 		void InitSound()
 		{
 			resampler = new Sound.Utilities.SpeexResampler(2, 2097152, 44100, 2097152, 44100, null, this);
-			dcfilter = new Sound.Utilities.DCFilter(resampler, 65536);
+			dcfilter = Sound.Utilities.DCFilter.AsISyncSoundProvider(resampler, 65536);
 		}
 
 		void DisposeSound()

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Namcot1xx/Namco163Audio.cs

@@ -125,7 +125,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		public Namco163Audio()
 		{
 			resampler = new Sound.Utilities.SpeexResampler(2, 119318, 44100, 119318, 44100, null, null);
-			dc = new Sound.Utilities.DCFilter(4096);
+			dc = Sound.Utilities.DCFilter.DetatchedMode(4096);
 			metaspu = new Sound.MetaspuAsync(resampler, Sound.ESynchMethod.ESynchMethod_V);
 		}
 

BizHawk.Emulation/Consoles/Nintendo/NES/FDS/FDSAudio.cs

@@ -309,7 +309,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			return ret;
 		}
 
-		Sound.Utilities.DCFilter dc = new Sound.Utilities.DCFilter(4096);
+		Sound.Utilities.DCFilter dc = Sound.Utilities.DCFilter.DetatchedMode(4096);
 
 		public void ApplyCustomAudio(short[] samples)
 		{

BizHawk.Emulation/Sound/Utilities/DCFilter.cs

@@ -27,53 +27,42 @@ namespace BizHawk.Emulation.Sound.Utilities
 
 		int depth;
 		
-		/// <summary>
+		public static DCFilter AsISoundProvider(ISoundProvider input, int filterwidth)
-		/// if input == null, run in detatched push mode
+		{
-		/// </summary>
+			if (input == null)
-		/// <param name="input"></param>
+				throw new ArgumentNullException();
-		public DCFilter(ISoundProvider input = null, int filterwidth = 65536)
+			return new DCFilter(input, null, filterwidth);
+		}
+
+		public static DCFilter AsISyncSoundProvider(ISyncSoundProvider syncinput, int filterwidth)
+		{
+			if (syncinput == null)
+				throw new ArgumentNullException();
+			return new DCFilter(null, syncinput, filterwidth);
+		}
+
+		public static DCFilter DetatchedMode(int filterwidth)
+		{
+			return new DCFilter(null, null, filterwidth);
+		}
+
+		DCFilter(ISoundProvider input, ISyncSoundProvider syncinput, int filterwidth)	
 		{
 			if (filterwidth < 1 || filterwidth > 65536)
 				throw new ArgumentOutOfRangeException();
 			this.input = input;
-			this.syncinput = null;
+			this.syncinput = syncinput;
-			this.depth = filterwidth;
+			depth = filterwidth;
-			this.buffer = new Queue<short>(depth * 2);
+			buffer = new Queue<short>(depth * 2);
 			for (int i = 0; i < depth * 2; i++)
 				buffer.Enqueue(0);
 		}
 		
 		/// <summary>
-		/// detached mode
+		/// pass a set of samples through the filter.  should only be used in detached mode
-		/// </summary>
-		/// <param name="filterwidth"></param>
-		public DCFilter(int filterwidth)
-		{
-			if (filterwidth < 1 || filterwidth > 65536)
-				throw new ArgumentOutOfRangeException();
-			this.input = null;
-			this.syncinput = null;
-			this.depth = filterwidth;
-			this.buffer = new Queue<short>(depth * 2);
-			for (int i = 0; i < depth * 2; i++)
-				buffer.Enqueue(0);
-		}
-
-		public DCFilter(ISyncSoundProvider input, int filterwidth)
-		{
-			if (filterwidth < 1 || filterwidth > 65536)
-				throw new ArgumentOutOfRangeException();
-			this.input = null;
-			this.syncinput = input;
-			this.depth = filterwidth;
-			this.buffer = new Queue<short>(depth * 2);
-			for (int i = 0; i < depth * 2; i++)
-				buffer.Enqueue(0);
-		}
-		
-		/// <summary>
-		/// pass a set of samples through the filter.  should not be mixed with pull (ISoundProvider) mode or sync mode
 		/// </summary>
+		/// <param name="samples">sample buffer to modify</param>
+		/// <param name="length">number of samples (not pairs).  stereo</param>
 		public void PushThroughSamples(short[] samples, int length)
 		{
 			PushThroughSamples(samples, samples, length);
@@ -107,36 +96,26 @@ namespace BizHawk.Emulation.Sound.Utilities
 				else
 					samplesout[i + 1] = (short)bigR;
 			}
-
 		}
 
-		public void GetSamples(short[] samples)
+		void ISoundProvider.GetSamples(short[] samples)
 		{
 			input.GetSamples(samples);
 			PushThroughSamples(samples, samples.Length);
 		}
 
-		public void DiscardSamples()
+		void ISoundProvider.DiscardSamples()
 		{
-			if (input != null)
+			input.DiscardSamples();
-				input.DiscardSamples();
-			if (syncinput != null)
-				syncinput.DiscardSamples();
 		}
 
-		public int MaxVolume
+		int ISoundProvider.MaxVolume
 		{
-			get
+			get { return input.MaxVolume; }
-			{
+			set { input.MaxVolume = value; }
-				return input.MaxVolume;
-			}
-			set
-			{
-				input.MaxVolume = value;
-			}
 		}
 
-		public void GetSamples(out short[] samples, out int nsamp)
+		void ISyncSoundProvider.GetSamples(out short[] samples, out int nsamp)
 		{
 			short[] sampin;
 			int nsampin;
@@ -146,5 +125,10 @@ namespace BizHawk.Emulation.Sound.Utilities
 			samples = ret;
 			nsamp = nsampin;
 		}
+
+		void ISyncSoundProvider.DiscardSamples()
+		{
+			syncinput.DiscardSamples();
+		}
 	}
 }