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@318: #include "system/System.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@315:     int fadeLength = 100; // 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@315: //    cerr << "ContinuousSynth::mix: f0 = " << f0 << " (from " << m_prevF0 << "), phase = " << m_phase << endl;
Chris@313: 
Chris@313:     for (int i = 0; i < m_blockSize; ++i) {
Chris@313: 
Chris@315:         double fHere = (nowOn ? f0 : m_prevF0);
Chris@315: 
Chris@315:         if (wasOn && nowOn && (f0 != m_prevF0) && (i < fadeLength)) {
Chris@315:             // interpolate the frequency shift
Chris@315:             fHere = m_prevF0 + ((f0 - m_prevF0) * i) / fadeLength;
Chris@315:         }
Chris@315: 
Chris@315:         double phasor = (fHere * 2 * M_PI) / m_sampleRate;
Chris@315:     
Chris@315: 	m_phase = m_phase + phasor;
Chris@313: 
Chris@318:         int harmonics = (m_sampleRate / 4) / fHere - 1;
Chris@318:         if (harmonics < 1) harmonics = 1;
Chris@313: 
Chris@318:         for (int h = 0; h < harmonics; ++h) {
Chris@318:             
Chris@318:             double hn = h*2 + 1;
Chris@318:             double hp = m_phase * hn;
Chris@318:             double v = sin(hp) / hn;
Chris@318: 
Chris@318:             if (!wasOn && i < fadeLength) {
Chris@318:                 // fade in
Chris@318:                 v = v * (i / double(fadeLength));
Chris@318:             } else if (!nowOn) {
Chris@318:                 // fade out
Chris@318:                 if (i > fadeLength) v = 0;
Chris@318:                 else v = v * (1.0 - (i / double(fadeLength)));
Chris@318:             }
Chris@318: 
Chris@318:             for (int c = 0; c < m_channels; ++c) {
Chris@318:                 toBuffers[c][i] += levels[c] * v;
Chris@318:             }
Chris@318:         }
Chris@313:     }	
Chris@313: 
Chris@313:     m_prevF0 = f0;
Chris@313: 
Chris@313:     delete[] levels;
Chris@313: }
Chris@313: