# HG changeset patch
# User Chris Cannam <c.cannam@qmul.ac.uk>
# Date 1234270363 0
# Node ID c8908cdc8c32f14c837dc116a482c88b8bfa8973
# Parent  833ca65b08203373c35a57acf4220fde11cf8dcb
* First cut at Matthew's downbeat estimator -- untested so far

diff -r 833ca65b0820 -r c8908cdc8c32 dsp/onsets/DetectionFunction.cpp
--- a/dsp/onsets/DetectionFunction.cpp	Mon Feb 09 16:05:32 2009 +0000
+++ b/dsp/onsets/DetectionFunction.cpp	Tue Feb 10 12:52:43 2009 +0000
@@ -38,7 +38,6 @@
     m_halfLength = m_dataLength/2;
 
     m_DFType = Config.DFType;
-    m_stepSecs = Config.stepSecs;
     m_stepSize = Config.stepSize;
 
     m_whiten = Config.adaptiveWhitening;
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/onsets/DetectionFunction.h
--- a/dsp/onsets/DetectionFunction.h	Mon Feb 09 16:05:32 2009 +0000
+++ b/dsp/onsets/DetectionFunction.h	Tue Feb 10 12:52:43 2009 +0000
@@ -23,7 +23,6 @@
 #define DF_BROADBAND (5)
 
 struct DFConfig{
-    double stepSecs; // DF step in seconds
     unsigned int stepSize; // DF step in samples
     unsigned int frameLength; // DF analysis window - usually 2*step
     int DFType; // type of detection function ( see defines )
@@ -59,7 +58,6 @@
     int m_DFType;
     unsigned int m_dataLength;
     unsigned int m_halfLength;
-    double m_stepSecs;
     unsigned int m_stepSize;
     double m_dbRise;
     bool m_whiten;
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/rateconversion/Decimator.h
--- a/dsp/rateconversion/Decimator.h	Mon Feb 09 16:05:32 2009 +0000
+++ b/dsp/rateconversion/Decimator.h	Tue Feb 10 12:52:43 2009 +0000
@@ -16,6 +16,16 @@
     void process( const double* src, double* dst );
     void doAntiAlias( const double* src, double* dst, unsigned int length );
 
+    /**
+     * Construct a Decimator to operate on input blocks of length
+     * inLength, with decimation factor decFactor.  inLength should be
+     * a multiple of decFactor.  Output blocks will be of length
+     * inLength / decFactor.
+     *
+     * decFactor must be a power of two.  The highest supported factor
+     * is obtained through getHighestSupportedFactor(); for higher
+     * factors, you will need to chain more than one decimator.
+     */
     Decimator( unsigned int inLength, unsigned int decFactor );
     virtual ~Decimator();
 
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/tempotracking/DownBeat.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/tempotracking/DownBeat.cpp	Tue Feb 10 12:52:43 2009 +0000
@@ -0,0 +1,241 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    QM DSP Library
+
+    Centre for Digital Music, Queen Mary, University of London.
+    This file copyright 2008-2009 Matthew Davies and QMUL.
+    All rights reserved.
+*/
+
+#include "DownBeat.h"
+
+#include "maths/MathAliases.h"
+#include "maths/MathUtilities.h"
+#include "dsp/transforms/FFT.h"
+
+#include <iostream>
+#include <cstdlib>
+
+DownBeat::DownBeat(float originalSampleRate,
+                   size_t decimationFactor,
+                   size_t dfIncrement) :
+    m_rate(originalSampleRate),
+    m_factor(decimationFactor),
+    m_increment(dfIncrement),
+    m_decimator1(0),
+    m_decimator2(0),
+    m_buffer(0),
+    m_bufsiz(0),
+    m_buffill(0),
+    m_beatframesize(0),
+    m_beatframe(0)
+{
+    // beat frame size is next power of two up from 1.3 seconds at the
+    // downsampled rate (happens to produce 4096 for 44100 or 48000 at
+    // 16x decimation, which is our expected normal situation)
+    int bfs = int((m_rate / decimationFactor) * 1.3);
+    m_beatframesize = 1;
+    while (bfs) { bfs >>= 1; m_beatframesize <<= 1; }
+    std::cerr << "rate = " << m_rate << ", bfs = " << m_beatframesize << std::endl;
+    m_beatframe = new double[m_beatframesize];
+    m_fftRealOut = new double[m_beatframesize];
+    m_fftImagOut = new double[m_beatframesize];
+}
+
+DownBeat::~DownBeat()
+{
+    delete m_decimator1;
+    delete m_decimator2;
+    if (m_buffer) free(m_buffer);
+    delete[] m_decbuf;
+    delete[] m_beatframe;
+    delete[] m_fftRealOut;
+    delete[] m_fftImagOut;
+}
+
+void
+DownBeat::makeDecimators()
+{
+    if (m_factor < 2) return;
+    int highest = Decimator::getHighestSupportedFactor();
+    if (m_factor <= highest) {
+        m_decimator1 = new Decimator(m_increment, m_factor);
+        return;
+    }
+    m_decimator1 = new Decimator(m_increment, highest);
+    m_decimator2 = new Decimator(m_increment / highest, m_factor / highest);
+    m_decbuf = new double[m_factor / highest];
+}
+
+void
+DownBeat::pushAudioBlock(const double *audio)
+{
+    if (m_buffill + (m_increment / m_factor) > m_bufsiz) {
+        if (m_bufsiz == 0) m_bufsiz = m_increment * 16;
+        else m_bufsiz = m_bufsiz * 2;
+        if (!m_buffer) {
+            m_buffer = (double *)malloc(m_bufsiz * sizeof(double));
+        } else {
+            std::cerr << "DownBeat::pushAudioBlock: realloc m_buffer to " << m_bufsiz << std::endl;
+            m_buffer = (double *)realloc(m_buffer, m_bufsiz * sizeof(double));
+        }
+    }
+    if (!m_decimator1) makeDecimators();
+    if (m_decimator2) {
+        m_decimator1->process(audio, m_decbuf);
+        m_decimator2->process(m_decbuf, m_buffer + m_buffill);
+    } else {
+        m_decimator1->process(audio, m_buffer + m_buffill);
+    }
+    m_buffill += m_increment / m_factor;
+}
+    
+const double *
+DownBeat::getBufferedAudio(size_t &length) const
+{
+    length = m_buffill;
+    return m_buffer;
+}
+
+void
+DownBeat::findDownBeats(const double *audio,
+                        size_t audioLength,
+                        const d_vec_t &beats,
+                        i_vec_t &downbeats)
+{
+    // FIND DOWNBEATS BY PARTITIONING THE INPUT AUDIO FILE INTO BEAT SEGMENTS
+    // WHERE THE AUDIO FRAMES ARE DOWNSAMPLED  BY A FACTOR OF 16 (fs ~= 2700Hz)
+    // THEN TAKING THE JENSEN-SHANNON DIVERGENCE BETWEEN BEAT SYNCHRONOUS SPECTRAL FRAMES
+
+    // IMPLEMENTATION (MOSTLY) FOLLOWS:
+    //  DAVIES AND PLUMBLEY "A SPECTRAL DIFFERENCE APPROACH TO EXTRACTING DOWNBEATS IN MUSICAL AUDIO"
+    //  EUSIPCO 2006, FLORENCE, ITALY
+
+    d_vec_t newspec(m_beatframesize / 2); // magnitude spectrum of current beat
+    d_vec_t oldspec(m_beatframesize / 2); // magnitude spectrum of previous beat
+    d_vec_t specdiff;
+
+    if (audioLength == 0) return;
+
+    for (size_t i = 0; i + 1 < beats.size(); ++i) {
+
+        // Copy the extents of the current beat from downsampled array
+        // into beat frame buffer
+
+        size_t beatstart = (beats[i] * m_increment) / m_factor;
+        size_t beatend = (beats[i] * m_increment) / m_factor;
+        if (beatend >= audioLength) beatend = audioLength - 1;
+        if (beatend < beatstart) beatend = beatstart;
+        size_t beatlen = beatend - beatstart;
+
+        // Also apply a Hanning window to the beat frame buffer, sized
+        // to the beat extents rather than the frame size.  (Because
+        // the size varies, it's easier to do this by hand than use
+        // our Window abstraction.)
+
+        for (size_t j = 0; j < beatlen; ++j) {
+            double mul = 0.5 * (1.0 - cos(TWO_PI * (double(j) / double(beatlen))));
+            m_beatframe[j] = audio[beatstart + j] * mul;
+        }
+
+        for (size_t j = beatlen; j < m_beatframesize; ++j) {
+            m_beatframe[j] = 0.0;
+        }
+
+        // Now FFT beat frame
+        
+        FFT::process(m_beatframesize, false,
+                     m_beatframe, 0, m_fftRealOut, m_fftImagOut);
+        
+        // Calculate magnitudes
+
+        for (size_t j = 0; j < m_beatframesize/2; ++j) {
+            newspec[j] = sqrt(m_fftRealOut[j] * m_fftRealOut[j] +
+                              m_fftImagOut[j] * m_fftImagOut[j]);
+        }
+
+        // Preserve peaks by applying adaptive threshold
+
+        MathUtilities::adaptiveThreshold(newspec);
+
+        // Calculate JS divergence between new and old spectral frames
+
+        specdiff.push_back(measureSpecDiff(oldspec, newspec));
+
+        // Copy newspec across to old
+
+        for (size_t j = 0; j < m_beatframesize/2; ++j) {
+            oldspec[j] = newspec[j];
+        }
+    }
+
+    // We now have all spectral difference measures in specdiff
+
+    uint timesig = 4;   // SHOULD REPLACE THIS WITH A FIND_METER FUNCTION - OR USER PARAMETER
+    d_vec_t dbcand(timesig); // downbeat candidates
+
+    // look for beat transition which leads to greatest spectral change
+    for (int beat = 0; beat < timesig; ++beat) {
+        for (int example = beat; example < specdiff.size(); ++example) {
+            dbcand[beat] += (specdiff[example]) / timesig;
+        }
+    }
+
+    // first downbeat is beat at index of maximum value of dbcand
+    int dbind = MathUtilities::getMax(dbcand);
+
+    // remaining downbeats are at timesig intervals from the first
+    for (int i = dbind; i < beats.size(); i += timesig) {
+        downbeats.push_back(i);
+    }
+}
+
+double
+DownBeat::measureSpecDiff(d_vec_t oldspec, d_vec_t newspec)
+{
+    // JENSEN-SHANNON DIVERGENCE BETWEEN SPECTRAL FRAMES
+
+    uint SPECSIZE = 512;   // ONLY LOOK AT FIRST 512 SAMPLES OF SPECTRUM. 
+    if (SPECSIZE > oldspec.size()/4) {
+        SPECSIZE = oldspec.size()/4;
+    }
+    double SD = 0.;
+    double sd1 = 0.;
+
+    double sumnew = 0.;
+    double sumold = 0.;
+  
+    for (uint i = 0;i < SPECSIZE;i++)
+    {
+        newspec[i] +=EPS;
+        oldspec[i] +=EPS;
+        
+        sumnew+=newspec[i];
+        sumold+=oldspec[i];
+    } 
+    
+    for (uint i = 0;i < SPECSIZE;i++)
+    {
+        newspec[i] /= (sumnew);
+        oldspec[i] /= (sumold);
+        
+        // IF ANY SPECTRAL VALUES ARE 0 (SHOULDN'T BE ANY!) SET THEM TO 1
+        if (newspec[i] == 0)
+        {
+            newspec[i] = 1.;
+        }
+        
+        if (oldspec[i] == 0)
+        {
+            oldspec[i] = 1.;
+        }
+        
+        // JENSEN-SHANNON CALCULATION
+        sd1 = 0.5*oldspec[i] + 0.5*newspec[i];	
+        SD = SD + (-sd1*log(sd1)) + (0.5*(oldspec[i]*log(oldspec[i]))) + (0.5*(newspec[i]*log(newspec[i])));
+    }
+    
+    return SD;
+}
+
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/tempotracking/DownBeat.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/tempotracking/DownBeat.h	Tue Feb 10 12:52:43 2009 +0000
@@ -0,0 +1,107 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    QM DSP Library
+
+    Centre for Digital Music, Queen Mary, University of London.
+    This file copyright 2008-2009 Matthew Davies and QMUL.
+    All rights reserved.
+*/
+
+#ifndef DOWNBEAT_H
+#define DOWNBEAT_H
+
+#include <vector>
+
+#include "dsp/rateconversion/Decimator.h"
+
+using std::vector;
+
+/**
+ * This class takes an input audio signal and a sequence of beat
+ * locations (calculated e.g. by TempoTrackV2) and estimates which of
+ * the beat locations are downbeats (first beat of the bar).
+ * 
+ * The input audio signal is expected to have been downsampled to a
+ * very low sampling rate (e.g. 2700Hz).  A utility function for
+ * downsampling and buffering incoming block-by-block audio is
+ * provided.
+ */
+class DownBeat
+{
+public:
+    /**
+     * Construct a downbeat locator that will operate on audio at the
+     * downsampled by the given decimation factor from the given
+     * original sample rate, plus beats extracted from the same audio
+     * at the given original sample rate with the given frame
+     * increment.
+     *
+     * decimationFactor must be a power of two no greater than 64, and
+     * dfIncrement must be a multiple of decimationFactor.
+     */
+    DownBeat(float originalSampleRate,
+             size_t decimationFactor,
+             size_t dfIncrement);
+    ~DownBeat();
+
+    /**
+     * Estimate which beats are down-beats.
+     * 
+     * audio contains the input audio stream after downsampling, and
+     * audioLength contains the number of samples in this downsampled
+     * stream.
+     *
+     * beats contains a series of beat positions expressed in
+     * multiples of the df increment at the audio's original sample
+     * rate, as described to the constructor.
+     *
+     * The returned downbeat array contains a series of indices to the
+     * beats array.
+     */
+    void findDownBeats(const double *audio, // downsampled
+                       size_t audioLength, // after downsampling
+                       const vector<double> &beats,
+                       vector<int> &downbeats);
+    
+    /**
+     * For your downsampling convenience: call this function
+     * repeatedly with input audio blocks containing dfIncrement
+     * samples at the original sample rate, to decimate them to the
+     * downsampled rate and buffer them within the DownBeat class.
+     *     
+     * Call getBufferedAudio() to retrieve the results after all
+     * blocks have been processed.
+     */
+    void pushAudioBlock(const double *audio);
+    
+    /**
+     * Retrieve the accumulated audio produced by pushAudioBlock calls.
+     */
+    const double *getBufferedAudio(size_t &length) const;
+
+private:
+    typedef vector<int> i_vec_t;
+    typedef vector<vector<int> > i_mat_t;
+    typedef vector<double> d_vec_t;
+    typedef vector<vector<double> > d_mat_t;
+
+    void makeDecimators();
+    double measureSpecDiff(d_vec_t oldspec, d_vec_t newspec);
+
+    float m_rate;
+    size_t m_factor;
+    size_t m_increment;
+    Decimator *m_decimator1;
+    Decimator *m_decimator2;
+    double *m_buffer;
+    double *m_decbuf;
+    size_t m_bufsiz;
+    size_t m_buffill;
+    size_t m_beatframesize;
+    double *m_beatframe;
+    double *m_fftRealOut;
+    double *m_fftImagOut;
+};
+
+#endif
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/tempotracking/TempoTrackV2.cpp
--- a/dsp/tempotracking/TempoTrackV2.cpp	Mon Feb 09 16:05:32 2009 +0000
+++ b/dsp/tempotracking/TempoTrackV2.cpp	Tue Feb 10 12:52:43 2009 +0000
@@ -14,69 +14,15 @@
 #include <cstdlib>
 #include <iostream>
 
+#include "maths/MathUtilities.h"
 
-//#define		FRAMESIZE	512
-//#define		BIGFRAMESIZE	1024
-#define   TWOPI 6.283185307179586232
 #define   EPS 0.0000008 // just some arbitrary small number
 
-TempoTrackV2::TempoTrackV2() { }
+TempoTrackV2::TempoTrackV2(float rate, size_t increment) :
+    m_rate(rate), m_increment(increment) { }
 TempoTrackV2::~TempoTrackV2() { }
 
 void
-TempoTrackV2::adapt_thresh(d_vec_t &df)
-{
-    d_vec_t smoothed(df.size());
-	
-    int p_post = 7;
-    int p_pre = 8;
-
-    int t = std::min(static_cast<int>(df.size()),p_post);	// what is smaller, p_post of df size. This is to avoid accessing outside of arrays
-
-    // find threshold for first 't' samples, where a full average cannot be computed yet 
-    for (int i = 0;i <= t;i++)
-    {	
-        int k = std::min((i+p_pre),static_cast<int>(df.size()));
-        smoothed[i] = mean_array(df,1,k);
-    }
-    // find threshold for bulk of samples across a moving average from [i-p_pre,i+p_post]
-    for (uint i = t+1;i < df.size()-p_post;i++)
-    {
-        smoothed[i] = mean_array(df,i-p_pre,i+p_post);
-    }
-    // for last few samples calculate threshold, again, not enough samples to do as above
-    for (uint i = df.size()-p_post;i < df.size();i++)
-    {
-        int k = std::max((static_cast<int> (i) -p_post),1);
-        smoothed[i] = mean_array(df,k,df.size());
-    }
-
-    // subtract the threshold from the detection function and check that it is not less than 0
-    for (uint i = 0;i < df.size();i++)
-    {
-        df[i] -= smoothed[i];
-        if (df[i] < 0)
-        {
-            df[i] = 0;
-        }
-    }
-}
-
-double
-TempoTrackV2::mean_array(const d_vec_t &dfin,int start,int end)
-{
-    double sum = 0.;
-	
-    // find sum
-    for (int i = start;i < end;i++)
-    {
-        sum += dfin[i];
-    }
-
-    return static_cast<double> (sum / (end - start + 1) );	// average and return
-}
-
-void
 TempoTrackV2::filter_df(d_vec_t &df)
 {
     d_vec_t a(3);
@@ -205,7 +151,7 @@
 
     d_vec_t dfframe(dfframe_in);
 
-    adapt_thresh(dfframe);
+    MathUtilities::adaptiveThreshold(dfframe);
 
     d_vec_t acf(dfframe.size());
 
@@ -238,7 +184,7 @@
     }
   
     // apply adaptive threshold to rcf
-    adapt_thresh(rcf);
+    MathUtilities::adaptiveThreshold(rcf);
   
     double rcfsum =0.;
     for (uint i=0; i<rcf.size(); i++)
@@ -390,7 +336,7 @@
 
     for (uint i = 0; i < beat_period.size(); i++)
     {
-        tempi.push_back((60.*44100./512.)/beat_period[i]);
+        tempi.push_back((60. * m_rate / m_increment)/beat_period[i]);
     }
 }
 
diff -r 833ca65b0820 -r c8908cdc8c32 dsp/tempotracking/TempoTrackV2.h
--- a/dsp/tempotracking/TempoTrackV2.h	Mon Feb 09 16:05:32 2009 +0000
+++ b/dsp/tempotracking/TempoTrackV2.h	Tue Feb 10 12:52:43 2009 +0000
@@ -16,16 +16,31 @@
 
 using std::vector;
 
+//!!! Question: how far is this actually sample rate dependent?  I
+// think it does produce plausible results for e.g. 48000 as well as
+// 44100, but surely the fixed window sizes and comb filtering will
+// make it prefer double or half time when run at e.g. 96000?
+
 class TempoTrackV2  
 {
 public:
-    TempoTrackV2();
+    /**
+     * Construct a tempo tracker that will operate on beat detection
+     * function data calculated from audio at the given sample rate
+     * with the given frame increment.
+     *
+     * Currently the sample rate and increment are used only for the
+     * conversion from beat frame location to bpm in the tempo array.
+     */
+    TempoTrackV2(float sampleRate, size_t dfIncrement);
     ~TempoTrackV2();
 
+    // Returned beat periods are given in df increment units; tempi in bpm
     void calculateBeatPeriod(const vector<double> &df,
                              vector<double> &beatPeriod,
                              vector<double> &tempi);
 
+    // Returned beat positions are given in df increment units
     void calculateBeats(const vector<double> &df,
                         const vector<double> &beatPeriod,
                         vector<double> &beats);
@@ -36,6 +51,9 @@
     typedef vector<double> d_vec_t;
     typedef vector<vector<double> > d_mat_t;
 
+    float m_rate;
+    size_t m_increment;
+
     void adapt_thresh(d_vec_t &df);
     double mean_array(const d_vec_t &dfin, int start, int end);
     void filter_df(d_vec_t &df);
diff -r 833ca65b0820 -r c8908cdc8c32 maths/MathAliases.h
--- a/maths/MathAliases.h	Mon Feb 09 16:05:32 2009 +0000
+++ b/maths/MathAliases.h	Tue Feb 10 12:52:43 2009 +0000
@@ -22,7 +22,7 @@
 #define PI (3.14159265358979232846)
 #endif
 
-#define TWO_PI 		(*2.PI)
+#define TWO_PI 		(2. * PI)
 
 #define EPS 2.2204e-016
 
diff -r 833ca65b0820 -r c8908cdc8c32 maths/MathUtilities.cpp
--- a/maths/MathUtilities.cpp	Mon Feb 09 16:05:32 2009 +0000
+++ b/maths/MathUtilities.cpp	Tue Feb 10 12:52:43 2009 +0000
@@ -144,6 +144,20 @@
     return retVal;
 }
 
+double MathUtilities::mean(const std::vector<double> &src,
+                           unsigned int start,
+                           unsigned int count)
+{
+    double sum = 0.;
+	
+    for (int i = 0; i < count; ++i)
+    {
+        sum += src[start + i];
+    }
+
+    return sum / count;
+}
+
 void MathUtilities::getFrameMinMax(const double *data, unsigned int len, double *min, double *max)
 {
     unsigned int i;
@@ -189,7 +203,33 @@
 		
    	}
 
-	*pMax = max;
+	if (pMax) *pMax = max;
+
+
+	return index;
+}
+
+int MathUtilities::getMax( const std::vector<double> & data, double* pMax )
+{
+	unsigned int index = 0;
+	unsigned int i;
+	double temp = 0.0;
+	
+	double max = data[0];
+
+	for( i = 0; i < data.size(); i++)
+	{
+		temp = data[ i ];
+
+		if( temp > max )
+		{
+			max =  temp ;
+			index = i;
+		}
+		
+   	}
+
+	if (pMax) *pMax = max;
 
 
 	return index;
@@ -289,5 +329,28 @@
     }
 }
 
+void MathUtilities::adaptiveThreshold(std::vector<double> &data)
+{
+    int sz = int(data.size());
+    if (sz == 0) return;
+
+    std::vector<double> smoothed(sz);
+	
+    int p_pre = 8;
+    int p_post = 7;
+
+    for (int i = 0; i < sz; ++i) {
+
+        int first = std::max(0,      i - p_pre);
+        int last  = std::min(sz - 1, i + p_post);
+
+        smoothed[i] = mean(data, first, last - first + 1);
+    }
+
+    for (int i = 0; i < sz; i++) {
+        data[i] -= smoothed[i];
+        if (data[i] < 0.0) data[i] = 0.0;
+    }
+}
 
         
diff -r 833ca65b0820 -r c8908cdc8c32 maths/MathUtilities.h
--- a/maths/MathUtilities.h	Mon Feb 09 16:05:32 2009 +0000
+++ b/maths/MathUtilities.h	Tue Feb 10 12:52:43 2009 +0000
@@ -21,6 +21,8 @@
     static void	  getFrameMinMax( const double* data, unsigned int len,  double* min, double* max );
 
     static double mean( const double* src, unsigned int len );
+    static double mean( const std::vector<double> &data,
+                        unsigned int start, unsigned int count );
     static double sum( const double* src, unsigned int len );
     static double median( const double* src, unsigned int len );
 
@@ -32,7 +34,8 @@
 
     static void   circShift( double* data, int length, int shift);
 
-    static int	  getMax( double* data, unsigned int length, double* max );
+    static int	  getMax( double* data, unsigned int length, double* max = 0 );
+    static int	  getMax( const std::vector<double> &data, double* max = 0 );
     static int    compareInt(const void * a, const void * b);
 
     enum NormaliseType {
@@ -46,6 +49,9 @@
 
     static void   normalise(std::vector<double> &data,
                             NormaliseType n = NormaliseUnitMax);
+
+    // moving mean threshholding:
+    static void adaptiveThreshold(std::vector<double> &data);
 };
 
 #endif
diff -r 833ca65b0820 -r c8908cdc8c32 qm-dsp.pro
--- a/qm-dsp.pro	Mon Feb 09 16:05:32 2009 +0000
+++ b/qm-dsp.pro	Tue Feb 10 12:52:43 2009 +0000
@@ -48,6 +48,7 @@
            dsp/signalconditioning/Filter.h \
            dsp/signalconditioning/FiltFilt.h \
            dsp/signalconditioning/Framer.h \
+           dsp/tempotracking/DownBeat.h \
            dsp/tempotracking/TempoTrack.h \
            dsp/tempotracking/TempoTrackV2.h \
            dsp/tonal/ChangeDetectionFunction.h \
@@ -83,6 +84,7 @@
            dsp/signalconditioning/Filter.cpp \
            dsp/signalconditioning/FiltFilt.cpp \
            dsp/signalconditioning/Framer.cpp \
+           dsp/tempotracking/DownBeat.cpp \
            dsp/tempotracking/TempoTrack.cpp \
            dsp/tempotracking/TempoTrackV2.cpp \
            dsp/tonal/ChangeDetectionFunction.cpp \