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lib/BeatDetection2.h

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+#ifndef BEATDETECTION2_H
+#define BEATDETECTION2_H
+
+
+
+
+#include "BiquadFilterGate.h"
+#include "MovingAVG.h"
+#include "EndlessAVG.h"
+
+#include <iostream>
+
+//#define PLOT_ME
+
+#ifdef PLOT_ME
+    #include <KLib/misc/gnuplot/Gnuplot.h>
+    #include <KLib/misc/gnuplot/GnuplotPlot.h>
+    #include <KLib/misc/gnuplot/GnuplotPlotElementLines.h>
+    #include <KLib/misc/gnuplot/GnuplotSplot.h>
+#endif
+
+#define BD2_SHORT   1024
+
+template <typename Scalar> struct BeatBand2 {
+
+	BiquadFilterGate<2> filter;
+	MovingAVG<float> avgShort;
+	MovingAVG<float> avgLong;
+	MovingAVG<float> avgLongSquared;
+	MovingAVG<float> avgDiff;
+	MovingAVG<float> avgDiffSquared;
+
+
+
+
+    BeatBand2() : avgShort(BD2_SHORT), avgLong(1024*64), avgLongSquared(1024*64), avgDiff(1024*80), avgDiffSquared(1024*80) {
+		;
+	}
+
+	void add(Scalar left, Scalar right) {
+
+		// filter
+        const Scalar fLeft = std::abs(filter.filter(0, left));
+        const Scalar fRight = std::abs(filter.filter(1, right));
+        //const Scalar energy = fLeft*fLeft + fRight*fRight;
+        //const Scalar energy = fLeft + fRight;
+        const Scalar energy = fLeft*fLeft*fLeft + fRight*fRight*fRight;
+
+		// update
+		avgShort.add(energy);
+		avgLong.add(energy);
+		avgLongSquared.add(energy*energy);
+
+		const float diff = avgShort.get() - avgLong.get();
+		avgDiff.add(diff);
+		avgDiffSquared.add(diff*diff);
+
+	}
+
+	float getRatio() const {
+		return avgShort.get() / avgLong.get();
+	}
+
+	float getVariance() const {
+		return avgLongSquared.get() - (avgLong.get() * avgLong.get());
+	}
+
+	float getStdDev() const {
+		return std::sqrt(getVariance());
+	}
+
+	float getDiffVariance() const {
+		return avgDiffSquared.get() - (avgDiff.get() * avgDiff.get());
+	}
+	float getDiffStdDev() const {
+		return std::sqrt(getDiffVariance());
+	}
+
+};
+
+enum class Mode {
+    BASS,
+    SNARE,
+};
+
+template <typename Scalar> class BeatDetection2 {
+
+private:
+
+#ifdef PLOT_ME
+	K::Gnuplot gp;
+	K::GnuplotPlot plot;
+	K::GnuplotPlotElementLines lines0;
+	K::GnuplotPlotElementLines linesVar;
+	K::GnuplotPlotElementLines linesAvgLong;
+#endif
+
+	int cnt = 0;
+	BeatBand2<float> band0;
+    Mode mode;
+    float thresholdMul;
+
+public:
+
+    BeatDetection2() : BeatDetection2(Mode::BASS) {
+        ;
+    }
+
+	/** setup */
+    BeatDetection2(Mode mode) : mode(mode)  {
+
+        setSampleRate(44100);
+
+        switch(mode) {
+            case Mode::BASS:    thresholdMul = 0.9; break;
+            case Mode::SNARE:   thresholdMul = 1.5; break;
+            default:            throw "invalid mode";
+        }
+
+#ifdef PLOT_ME
+        gp.setTerminal("wxt", K::GnuplotSize(20, 12));
+		plot.add(&lines0);
+		plot.add(&linesVar); linesVar.getStroke().getColor().setHexStr("#0000ff");
+		plot.add(&linesAvgLong); linesAvgLong.getStroke().getColor().setHexStr("#00aa00");
+#endif
+	}
+
+
+
+	void setSampleRate(int srate) {
+		std::cout << "setting sample-rate to " << srate << std::endl;
+        //band0.filter.setLowPass(110, 1, srate);
+        switch(mode) {
+            case Mode::BASS:    band0.filter.setBandPass(40, 0.90f, srate); break;
+            case Mode::SNARE:   band0.filter.setBandPass(200, 0.20f, srate); break;
+            default:            throw "invalid mode";
+        }
+        //band0.filter.setBandPass(5000, 1, srate);
+	}
+
+	int block = 0;
+	bool lastWasBeat = false;
+	bool gapFound = false;
+
+	/** add single value */
+	bool add(Scalar left, Scalar right) {
+
+		static int x = 0; ++x;
+
+		left /= 36768.0f;
+		right /= 36768.0f;
+
+		++cnt;
+		band0.add(left, right);
+		bool curIsBeat = false;
+
+        if (cnt == BD2_SHORT) {
+
+			cnt = 0;
+
+            //const float ratio0 = band0.getRatio();
+            //const float var0 = band0.getVariance();
+			const float stdDev0 = band0.getDiffStdDev();
+            //const float diff0 = band0.avgShort.get() - band0.avgLong.get();
+			const float avgShort0 = band0.avgShort.get();
+            //const float avgLong0 = band0.avgLong.get();
+            const float threshold0 = band0.avgLong.get() + stdDev0 * thresholdMul;      // HERE!
+
+
+            //avgRes.add(avgShort0);
+            //const float zz = avgRes.get();
+            const float zz = avgShort0;
+			//const float C = 2.7 - (20 * var0);
+			//const float C = 1.0 + (var0);
+			//if (ratio0 > C) {curIsBeat = true;}
+            //if (zz > 0.05 && zz > threshold0) {curIsBeat = true;}
+            if (zz > threshold0) {curIsBeat = true;}
+
+#ifdef PLOT_ME
+
+            lines0.add(K::GnuplotPoint2(x, zz));
+			linesVar.add(K::GnuplotPoint2(x, threshold0));
+			//linesAvgLong.add(K::GnuplotPoint2(x, avgLong0));
+
+			static int xx = 0; ++xx;
+			if (xx % 5 == 0) {
+				show();
+			}
+
+#endif
+
+			if (!curIsBeat) {gapFound = true;}
+
+			//if (block > 0 && !curIsBeat) {--block;}
+			if (block > 0 && gapFound) {--block;}
+
+			if (block == 0 && curIsBeat) {
+                block = 8;  // very short!
+				gapFound = false;
+				//std::cout << ratio0  << " : " << var0 << " : " << C << std::endl;
+				return true;
+			}
+
+			//const bool res = curIsBeat && !lastWasBeat;
+			//lastWasBeat = curIsBeat;
+
+//			if (res) {
+//				std::cout << ratio0  << " : " << var0 << " : " << C << std::endl;
+
+//			}
+
+			//return res;
+
+		}
+
+		return false;
+
+	}
+
+
+
+#ifdef PLOT_ME
+	void show() {
+
+		int limit = 200;
+		int d0 = lines0.size() - limit;
+		if (d0 > 0) {
+			lines0.remove(0, d0);
+		}
+
+		int x0 = lines0[0].x;
+		int x1 = lines0[lines0.size()-1].x;
+		plot.getAxisX().setRange(x0, x1);
+        //plot.getAxisY().setRange(-0.1, 0.25);
+		//plot.getAxisY().setRange(-32768, +32768);
+		gp.draw(plot);
+		gp.flush();
+
+	}
+#endif
+
+};
+
+#endif // BEATDETECTION2_H