Chris@313: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@313: 
Chris@313: /*
Chris@313:     Sonic Visualiser
Chris@313:     An audio file viewer and annotation editor.
Chris@313:     Centre for Digital Music, Queen Mary, University of London.
Chris@313:     
Chris@313:     This program is free software; you can redistribute it and/or
Chris@313:     modify it under the terms of the GNU General Public License as
Chris@313:     published by the Free Software Foundation; either version 2 of the
Chris@313:     License, or (at your option) any later version.  See the file
Chris@313:     COPYING included with this distribution for more information.
Chris@313: */
Chris@313: 
Chris@313: #include "ContinuousSynth.h"
Chris@313: 
Chris@313: #include "base/Debug.h"
Chris@313: 
Chris@313: #include <cmath>
Chris@313: 
Chris@313: ContinuousSynth::ContinuousSynth(int channels, int sampleRate, int blockSize) :
Chris@313:     m_channels(channels),
Chris@313:     m_sampleRate(sampleRate),
Chris@313:     m_blockSize(blockSize),
Chris@313:     m_prevF0(-1.f),
Chris@313:     m_phase(0.0)
Chris@313: {
Chris@313: }
Chris@313: 
Chris@313: ContinuousSynth::~ContinuousSynth()
Chris@313: {
Chris@313: }
Chris@313: 
Chris@313: void
Chris@313: ContinuousSynth::reset()
Chris@313: {
Chris@313:     m_phase = 0;
Chris@313: }
Chris@313: 
Chris@313: void
Chris@313: ContinuousSynth::mix(float **toBuffers, float gain, float pan, float f0)
Chris@313: {
Chris@313:     if (f0 == 0.f) f0 = m_prevF0;
Chris@313: 
Chris@313:     bool wasOn = (m_prevF0 > 0.f);
Chris@313:     bool nowOn = (f0 > 0.f);
Chris@313: 
Chris@313:     if (!nowOn && !wasOn) {
Chris@313: 	m_phase = 0;
Chris@313: 	return;
Chris@313:     }
Chris@313: 
Chris@313:     int fadeLength = 20; // samples
Chris@313: 
Chris@313:     float *levels = new float[m_channels];
Chris@313:     
Chris@313:     for (int c = 0; c < m_channels; ++c) {
Chris@313: 	levels[c] = gain;
Chris@313:     }
Chris@313:     if (pan != 0.0 && m_channels == 2) {
Chris@313: 	levels[0] *= 1.0 - pan;
Chris@313: 	levels[1] *= pan + 1.0;
Chris@313:     }
Chris@313: 
Chris@313:     double phasor = (f0 * 2 * M_PI) / m_sampleRate;
Chris@313:     double p = m_phase;
Chris@313: 
Chris@313:     cerr << "ContinuousSynth::mix: f0 = " << f0 << " (from " << m_prevF0 << "), phase = " << m_phase << ", phasor = " << phasor << endl;
Chris@313: 
Chris@313:     for (int i = 0; i < m_blockSize; ++i) {
Chris@313: 
Chris@313: 	p = m_phase + i * phasor;
Chris@313: 	
Chris@313: 	double v = sin(p);
Chris@313: 
Chris@313: 	if (!wasOn && i < fadeLength) { // fade in
Chris@313: 	    v = v * (i / double(fadeLength));
Chris@313: 	} else if (!nowOn) {
Chris@313: 	    if (i > fadeLength) v = 0;
Chris@313: 	    else v = v * (1.0 - (i / double(fadeLength)));
Chris@313: 	}
Chris@313: 
Chris@313: 	for (int c = 0; c < m_channels; ++c) {
Chris@313: 	    toBuffers[c][i] += levels[c] * v;
Chris@313: 	}
Chris@313:     }	
Chris@313: 
Chris@313:     m_prevF0 = f0;
Chris@313:     m_phase = p;
Chris@313: 
Chris@313:     delete[] levels;
Chris@313: }
Chris@313: