diff audioio/ContinuousSynth.cpp @ 313:58582119c92a tonioni

Add a basic continuous synth implementation (simple sinusoids only, no gaps)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/audioio/ContinuousSynth.cpp	Wed Jan 08 13:07:22 2014 +0000
@@ -0,0 +1,93 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Sonic Visualiser
+    An audio file viewer and annotation editor.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 "ContinuousSynth.h"
+
+#include "base/Debug.h"
+
+#include <cmath>
+
+ContinuousSynth::ContinuousSynth(int channels, int sampleRate, int blockSize) :
+    m_channels(channels),
+    m_sampleRate(sampleRate),
+    m_blockSize(blockSize),
+    m_prevF0(-1.f),
+    m_phase(0.0)
+{
+}
+
+ContinuousSynth::~ContinuousSynth()
+{
+}
+
+void
+ContinuousSynth::reset()
+{
+    m_phase = 0;
+}
+
+void
+ContinuousSynth::mix(float **toBuffers, float gain, float pan, float f0)
+{
+    if (f0 == 0.f) f0 = m_prevF0;
+
+    bool wasOn = (m_prevF0 > 0.f);
+    bool nowOn = (f0 > 0.f);
+
+    if (!nowOn && !wasOn) {
+	m_phase = 0;
+	return;
+    }
+
+    int fadeLength = 20; // samples
+
+    float *levels = new float[m_channels];
+    
+    for (int c = 0; c < m_channels; ++c) {
+	levels[c] = gain;
+    }
+    if (pan != 0.0 && m_channels == 2) {
+	levels[0] *= 1.0 - pan;
+	levels[1] *= pan + 1.0;
+    }
+
+    double phasor = (f0 * 2 * M_PI) / m_sampleRate;
+    double p = m_phase;
+
+    cerr << "ContinuousSynth::mix: f0 = " << f0 << " (from " << m_prevF0 << "), phase = " << m_phase << ", phasor = " << phasor << endl;
+
+    for (int i = 0; i < m_blockSize; ++i) {
+
+	p = m_phase + i * phasor;
+	
+	double v = sin(p);
+
+	if (!wasOn && i < fadeLength) { // fade in
+	    v = v * (i / double(fadeLength));
+	} else if (!nowOn) {
+	    if (i > fadeLength) v = 0;
+	    else v = v * (1.0 - (i / double(fadeLength)));
+	}
+
+	for (int c = 0; c < m_channels; ++c) {
+	    toBuffers[c][i] += levels[c] * v;
+	}
+    }	
+
+    m_prevF0 = f0;
+    m_phase = p;
+
+    delete[] levels;
+}
+