From 2a2caa492cd2d71ac0af49bfc1bf77f5b7345e48 Mon Sep 17 00:00:00 2001
From: goyuken <goyuken@4bbf4f03-6f44-549e-7e59-35d4b0962838>
Date: Sun, 19 Aug 2012 17:46:13 +0000
Subject: [PATCH] add linear resampler (not activated in code).  sounds about
 the same as the other two (ie, no major bugs) on the opening to Golden Axe

---
 BizHawk.Emulation/Sound/YM2612.cs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/BizHawk.Emulation/Sound/YM2612.cs b/BizHawk.Emulation/Sound/YM2612.cs
index 08a5bc02c3..e9cfb9a161 100644
--- a/BizHawk.Emulation/Sound/YM2612.cs
+++ b/BizHawk.Emulation/Sound/YM2612.cs
@@ -1031,6 +1031,7 @@ namespace BizHawk.Emulation.Sound
             // downsample from native output rate to 44100.
             //CrappyNaiveResampler(nativeSamples, samples);
             MaybeBetterDownsampler(nativeSamples, samples);
+			//LinearDownsampler(nativeSamples, samples);
         }
 
         static void CrappyNaiveResampler(short[] input, short[] output)
@@ -1052,6 +1053,30 @@ namespace BizHawk.Emulation.Sound
             return value - Math.Floor(value);
         }
 
+		/// <summary>
+		/// basic linear audio resampler. sampling rate is inferred from buffer sizes
+		/// </summary>
+		/// <param name="input">stereo s16</param>
+		/// <param name="output">stereo s16</param>
+		static void LinearDownsampler(short[] input, short[] output)
+		{
+			double samplefactor = input.Length / (double)output.Length;
+
+			for (int i = 0; i < output.Length / 2; i++)
+			{
+				// exact position on input stream
+				double inpos = i * samplefactor;
+				// selected interpolation points and weights
+				int pt0 = (int)inpos; // pt1 = pt0 + 1
+				double wt1 = inpos - pt0; // wt0 = 1 - wt1
+				double wt0 = 1.0 - wt1;
+
+				output[i * 2 + 0] = (short)(input[pt0 * 2 + 0] * wt0 + input[pt0 * 2 + 2] * wt1);
+				output[i * 2 + 1] = (short)(input[pt0 * 2 + 1] * wt0 + input[pt0 * 2 + 3] * wt1);
+			}
+		}
+
+
         static void MaybeBetterDownsampler(short[] input, short[] output)
         {
             // This is still not a good resampler. But it's better than the other one. Unsure how much difference it makes.