diff audio/ContinuousSynth.cpp @ 468:56acd9368532 bqaudioio

Initial work toward switching to bqaudioio library (so as to get I/O, not just O)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/audio/ContinuousSynth.cpp	Tue Aug 04 13:27:42 2015 +0100
@@ -0,0 +1,149 @@
+/* -*- 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 "system/System.h"
+
+#include <cmath>
+
+ContinuousSynth::ContinuousSynth(int channels, sv_samplerate_t sampleRate, sv_frame_t blockSize, int waveType) :
+    m_channels(channels),
+    m_sampleRate(sampleRate),
+    m_blockSize(blockSize),
+    m_prevF0(-1.0),
+    m_phase(0.0),
+    m_wavetype(waveType) // 0: 3 sinusoids, 1: 1 sinusoid, 2: sawtooth, 3: square
+{
+}
+
+ContinuousSynth::~ContinuousSynth()
+{
+}
+
+void
+ContinuousSynth::reset()
+{
+    m_phase = 0;
+}
+
+void
+ContinuousSynth::mix(float **toBuffers, float gain, float pan, float f0f)
+{
+    double f0(f0f);
+    if (f0 == 0.0) f0 = m_prevF0;
+
+    bool wasOn = (m_prevF0 > 0.0);
+    bool nowOn = (f0 > 0.0);
+
+    if (!nowOn && !wasOn) {
+        m_phase = 0;
+        return;
+    }
+
+    sv_frame_t fadeLength = 100;
+
+    float *levels = new float[m_channels];
+    
+    for (int c = 0; c < m_channels; ++c) {
+        levels[c] = gain * 0.5f; // scale gain otherwise too loud compared to source
+    }
+    if (pan != 0.0 && m_channels == 2) {
+        levels[0] *= 1.0f - pan;
+        levels[1] *= pan + 1.0f;
+    }
+
+//    cerr << "ContinuousSynth::mix: f0 = " << f0 << " (from " << m_prevF0 << "), phase = " << m_phase << endl;
+
+    for (sv_frame_t i = 0; i < m_blockSize; ++i) {
+
+        double fHere = (nowOn ? f0 : m_prevF0);
+
+        if (wasOn && nowOn && (f0 != m_prevF0) && (i < fadeLength)) {
+            // interpolate the frequency shift
+            fHere = m_prevF0 + ((f0 - m_prevF0) * double(i)) / double(fadeLength);
+        }
+
+        double phasor = (fHere * 2 * M_PI) / m_sampleRate;
+    
+        m_phase = m_phase + phasor;
+
+        int harmonics = int((m_sampleRate / 4) / fHere - 1);
+        if (harmonics < 1) harmonics = 1;
+
+        switch (m_wavetype) {
+        case 1:
+            harmonics = 1;
+            break;
+        case 2:
+            break;
+        case 3:
+            break;
+        default:
+            harmonics = 3;
+            break;
+        }
+
+        for (int h = 0; h < harmonics; ++h) {
+
+            double v = 0;
+            double hn = 0;
+            double hp = 0;
+
+            switch (m_wavetype) {
+            case 1: // single sinusoid
+                v = sin(m_phase);
+                break;
+            case 2: // sawtooth
+                if (h != 0) {
+                    hn = h + 1;
+                    hp = m_phase * hn;
+                    v = -(1.0 / M_PI) * sin(hp) / hn;
+                } else {
+                    v = 0.5;
+                }
+                break;
+            case 3: // square
+                hn = h*2 + 1;
+                hp = m_phase * hn;
+                v = sin(hp) / hn;
+                break;
+            default: // 3 sinusoids
+                hn = h + 1;
+                hp = m_phase * hn;
+                v = sin(hp) / hn;
+                break;
+            }
+
+            if (!wasOn && i < fadeLength) {
+                // fade in
+                v = v * (double(i) / double(fadeLength));
+            } else if (!nowOn) {
+                // fade out
+                if (i > fadeLength) v = 0;
+                else v = v * (1.0 - (double(i) / double(fadeLength)));
+            }
+
+            for (int c = 0; c < m_channels; ++c) {
+                toBuffers[c][i] += float(levels[c] * v);
+            }
+        }
+    }    
+
+    m_prevF0 = f0;
+
+    delete[] levels;
+}
+