98 lines
2.5 KiB
C#
98 lines
2.5 KiB
C#
// C# port of C-based 3-band equalizer (C) Neil C / Etanza Systems / 2006
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using System;
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namespace BizHawk.Emulation.Common
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{
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public sealed class Equalizer
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{
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private double lowFilter;
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private double lowFilterPole0;
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private double lowFilterPole1;
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private double lowFilterPole2;
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private double lowFilterPole3;
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private double highFilter;
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private double highFilterPole0;
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private double highFilterPole1;
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private double highFilterPole2;
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private double highFilterPole3;
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private double sampleDataMinus1;
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private double sampleDataMinus2;
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private double sampleDataMinus3;
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private double lowGain;
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private double midGain;
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private double highGain;
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private const double sampleRate = 44100.0;
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private const double verySmallAmount = 1.0 / 4294967295.0;
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private double lowfreq;
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public double LowFreqCutoff
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{
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get { return lowfreq; }
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set
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{
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lowfreq = value;
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lowFilter = 2 * Math.Sin(Math.PI * (lowfreq / sampleRate));
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}
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}
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private double highfreq;
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public double HighFreqCutoff
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{
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get { return highfreq; }
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set
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{
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highfreq = value;
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highFilter = 2 * Math.Sin(Math.PI * (highfreq / sampleRate));
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}
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}
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public Equalizer(double lowFreq = 880, double highFreq = 5000)
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{
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lowGain = 1.3;
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midGain = 0.9;
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highGain = 1.3;
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LowFreqCutoff = lowFreq;
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HighFreqCutoff = highFreq;
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}
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public short EqualizeSample(short sample)
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{
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lowFilterPole0 += (lowFilter * (sample - lowFilterPole0)) + verySmallAmount;
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lowFilterPole1 += lowFilter * (lowFilterPole0 - lowFilterPole1);
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lowFilterPole2 += lowFilter * (lowFilterPole1 - lowFilterPole2);
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lowFilterPole3 += lowFilter * (lowFilterPole2 - lowFilterPole3);
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double l = lowFilterPole3;
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highFilterPole0 += (highFilter * (sample - highFilterPole0)) + verySmallAmount;
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highFilterPole1 += highFilter * (highFilterPole0 - highFilterPole1);
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highFilterPole2 += highFilter * (highFilterPole1 - highFilterPole2);
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highFilterPole3 += highFilter * (highFilterPole2 - highFilterPole3);
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double h = sampleDataMinus3 - highFilterPole3;
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double m = sample - (h + l);
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l *= lowGain;
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m *= midGain;
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h *= highGain;
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sampleDataMinus3 = sampleDataMinus2;
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sampleDataMinus2 = sampleDataMinus1;
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sampleDataMinus1 = sample;
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return (short)(l + m + h);
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}
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public void Equalize(short[] samples)
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{
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for (int i = 0; i < samples.Length; i++)
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{
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samples[i] = EqualizeSample(samples[i]);
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}
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}
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}
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} |