copy from vendor branch, v1.0

git-svn-id: svn://localhost/ardour2/branches/2.0-ongoing@2775 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/rubberband/src/PercussiveAudioCurve.cpp

@@ -0,0 +1,78 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Rubber Band
+    An audio time-stretching and pitch-shifting library.
+    Copyright 2007 Chris Cannam.
+    
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#include "PercussiveAudioCurve.h"
+
+#include <cmath>
+
+namespace RubberBand
+{
+
+PercussiveAudioCurve::PercussiveAudioCurve(size_t sampleRate, size_t windowSize) :
+    AudioCurve(sampleRate, windowSize)
+{
+    m_prevMag = new double[m_windowSize/2 + 1];
+
+    for (size_t i = 0; i <= m_windowSize/2; ++i) {
+        m_prevMag[i] = 0.f;
+    }
+}
+
+PercussiveAudioCurve::~PercussiveAudioCurve()
+{
+    delete[] m_prevMag;
+}
+
+void
+PercussiveAudioCurve::reset()
+{
+    for (size_t i = 0; i <= m_windowSize/2; ++i) {
+        m_prevMag[i] = 0;
+    }
+}
+
+void
+PercussiveAudioCurve::setWindowSize(size_t newSize)
+{
+    delete[] m_prevMag;
+    m_windowSize = newSize;
+    
+    m_prevMag = new double[m_windowSize/2 + 1];
+
+    reset();
+}
+
+float
+PercussiveAudioCurve::process(float *mag, size_t increment)
+{
+    static float threshold = pow(10, 0.3);
+    static float zeroThresh = pow(10, -16);
+
+    size_t count = 0;
+    size_t nonZeroCount = 0;
+
+    for (size_t n = 1; n <= m_windowSize / 2; ++n) {
+	float sqrmag = mag[n] * mag[n];
+        bool above = ((sqrmag / m_prevMag[n]) >= threshold);
+        if (above) ++count;
+        if (sqrmag > zeroThresh) ++nonZeroCount;
+	m_prevMag[n] = sqrmag;
+    }
+
+    if (nonZeroCount == 0) return 0;
+    else return float(count) / float(nonZeroCount);
+}
+
+}
+