Initial community commit

Src/Winamp/benskiQ/EqBand.cpp

@@ -0,0 +1,81 @@
+#include "EqBand.h"
+#include <assert.h>
+#include <math.h>
+
+EqBand::EqBand() : sampleRate(44100), centerFrequency(1000), gain(1), _q(0.5), nch(0), channels(0), bypass(true)
+{
+}
+
+void EqBand::set_num_channels(int num_channels)
+{
+	if (nch < num_channels)
+	{
+		nch = num_channels;
+		delete[]channels;
+		channels = new Biquad[nch];
+		clear_buffers();
+		set_parameters(centerFrequency, gain, _q);
+	}
+}
+
+void EqBand::SetSampleRate(double sample_freq)
+{
+	if (sample_freq != sampleRate)
+	{
+		sampleRate = sample_freq;
+		for (int chn = 0; chn < nch; ++chn)
+		{
+			channels[chn].SetSampleRate(sampleRate);
+		}
+		clear_buffers();
+		set_parameters(centerFrequency, gain, _q);
+	}
+}
+
+void EqBand::set_parameters(double freq, double newGain, double q)
+{
+	centerFrequency = freq;
+	gain = newGain;
+	_q = q;
+
+	if (nch > 0)
+	{
+		Biquad & ref_filter = channels[0];
+
+		ref_filter.set_freq(centerFrequency);
+
+		double a[3] = { 1, 1/_q, 1 };
+		double b[3] = {1, gain / _q, 1};
+		ref_filter.set_s_eq(b, a);
+
+		ref_filter.transform_s_to_z();
+
+		for (int chn = 1; chn < nch; ++chn)
+			channels[chn].copy_filter(ref_filter);
+	}
+
+	bypass = (fabs(gain - 1.0) < 0.02); // About 1/4 dB
+}
+
+void EqBand::process(float ** const out, float ** in, long nbr_spl, int nbr_chn)
+{
+	assert(nbr_chn >= 0);
+	assert(nbr_chn <= nch);
+
+	if (!bypass)
+	{
+		for (int chn = 0; chn < nbr_chn; ++chn)
+		{
+			channels[chn].process_block(out[chn], in[chn], nbr_spl);
+		}
+	}
+}
+
+void EqBand::clear_buffers()
+{
+	for (int chn = 0; chn < nch; ++chn)
+	{
+		channels[chn].clear_buffers();
+	}
+}
+