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<h1 class="title">voiceanalyzer.cpp Example File</h1>
<span class="small-subtitle">demos/mobile/guitartuner/src/voiceanalyzer.cpp</span>
<!-- $$$demos/mobile/guitartuner/src/voiceanalyzer.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp"> <span class="comment">/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtDeclarative module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include "voiceanalyzer.h"</span>
<span class="comment">/**
* Constant used to scale the cut-off density for the fft helper.
*/</span>
<span class="keyword">const</span> <span class="keyword">static</span> <span class="type">float</span> CutOffScaler <span class="operator">=</span> <span class="number">0.05</span>;
<span class="comment">/**
* Force the precision to be "1/PrecisionPerNote" notes
* near the target frequency.
*/</span>
<span class="keyword">const</span> <span class="keyword">static</span> <span class="type">int</span> PrecisionPerNote <span class="operator">=</span> <span class="number">4</span>;
<span class="comment">/**
* TargetFrequencyParameter is a constant which implies the index at
* which corresponds to the target frequency.
* 0.5 * N * 1/TargetFrequencyParameter is (about) the index which
* corresponds to the given target frequency.
* Effectively TargetFrequencyParameter = 2^z, and the z*TargetFrequency
* is the maximum frequency that can be noticed.
*/</span>
<span class="keyword">const</span> <span class="keyword">static</span> <span class="type">int</span> TargetFrequencyParameter <span class="operator">=</span> <span class="number">4</span>;
VoiceAnalyzer<span class="operator">::</span>VoiceAnalyzer(<span class="keyword">const</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span> <span class="operator">&</span>format<span class="operator">,</span> <span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent):
<span class="type"><a href="qiodevice.html">QIODevice</a></span>(parent)<span class="operator">,</span>
m_format(format)<span class="operator">,</span>
m_frequency(<span class="number">0</span>)<span class="operator">,</span>
m_position(<span class="number">0</span>)<span class="operator">,</span>
m_fftHelper(<span class="keyword">new</span> FastFourierTransformer(<span class="keyword">this</span>))
{
Q_ASSERT(<a href="qvector3d.html#qFuzzyCompare">qFuzzyCompare</a>(M_SAMPLE_COUNT_MULTIPLIER<span class="operator">,</span>
<span class="type">float</span>(<span class="number">2</span>)<span class="operator">/</span>(M_TWELTH_ROOT_OF_2 <span class="operator">-</span><span class="number">1.0</span>)));
m_totalSampleCount <span class="operator">=</span> <a href="qtglobal.html#qRound">qRound</a>(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(PrecisionPerNote)
<span class="operator">*</span>TargetFrequencyParameter
<span class="operator">*</span>M_SAMPLE_COUNT_MULTIPLIER);
m_samples<span class="operator">.</span>reserve(m_totalSampleCount);
<span class="type">int</span> i <span class="operator">=</span> <span class="number">2</span>;
<span class="type">int</span> j <span class="operator">=</span> <span class="number">1</span>;
<span class="keyword">for</span> (; i <span class="operator"><</span> TargetFrequencyParameter; i <span class="operator">*</span><span class="operator">=</span> <span class="number">2</span>) {
j<span class="operator">+</span><span class="operator">+</span>;
}
m_maximumVoiceDifference <span class="operator">=</span> j<span class="operator">*</span><span class="number">12</span>;
setCutOffPercentage(CutOffScaler);
}
<span class="comment">/**
* Opens the parent QIODevice. Sets up the analysation parameters.
*/</span>
<span class="type">void</span> VoiceAnalyzer<span class="operator">::</span>start(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> frequency)
{
m_stepSize <span class="operator">=</span> (<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>) <span class="number">1.0</span> <span class="operator">*</span> m_format<span class="operator">.</span>sampleRate()
<span class="operator">/</span> (TargetFrequencyParameter<span class="operator">*</span><span class="number">2</span><span class="operator">*</span>frequency);
m_frequency <span class="operator">=</span> frequency;
open(<span class="type"><a href="qiodevice.html">QIODevice</a></span><span class="operator">::</span>WriteOnly);
}
<span class="comment">/**
* Closes the parent QIODevice, thus the voice is not analysed anymore.
* Resets the m_samples QList.
*/</span>
<span class="type">void</span> VoiceAnalyzer<span class="operator">::</span>stop()
{
m_samples<span class="operator">.</span>clear();
m_samples<span class="operator">.</span>reserve(m_totalSampleCount);
close();
}
<span class="comment">/**
* Called when data is obtained. Stores each m_stepSize sample
* into a QList to be analysed.
*/</span>
<span class="type"><a href="qtglobal.html#qint64-typedef">qint64</a></span> VoiceAnalyzer<span class="operator">::</span>writeData(<span class="keyword">const</span> <span class="type">char</span> <span class="operator">*</span>data<span class="operator">,</span> <span class="type"><a href="qtglobal.html#qint64-typedef">qint64</a></span> maxlen)
{
<span class="keyword">const</span> <span class="type">int</span> channelBytes <span class="operator">=</span> m_format<span class="operator">.</span>sampleSize() <span class="operator">/</span> <span class="number">8</span>;
<span class="type">int</span> sampleSize <span class="operator">=</span> m_format<span class="operator">.</span>channels() <span class="operator">*</span> channelBytes;
<span class="type">int</span> m_stepSizeInBytes <span class="operator">=</span> m_stepSize<span class="operator">*</span>sampleSize;
<span class="comment">// assert that each sample fits fully into the data</span>
Q_ASSERT((m_position <span class="operator">%</span> sampleSize)<span class="operator">=</span><span class="operator">=</span><span class="number">0</span>);
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#uchar-typedef">uchar</a></span> <span class="operator">*</span>ptr <span class="operator">=</span> <span class="keyword">reinterpret_cast</span><span class="operator"><</span><span class="keyword">const</span> <span class="type"><a href="qtglobal.html#uchar-typedef">uchar</a></span> <span class="operator">*</span><span class="operator">></span>(data);
<span class="keyword">while</span> (m_position <span class="operator"><</span> maxlen) {
<span class="keyword">if</span> (m_samples<span class="operator">.</span>size() <span class="operator"><</span> m_totalSampleCount) {
m_samples<span class="operator">.</span>append(getValueInt16(ptr<span class="operator">+</span>m_position));
}
<span class="keyword">else</span> {
analyzeVoice();
m_samples<span class="operator">.</span>clear();
m_samples<span class="operator">.</span>reserve(m_totalSampleCount);
<span class="comment">// fast forward position to the first position after maxlen or to the maxlen</span>
m_position <span class="operator">+</span><span class="operator">=</span> ((m_stepSizeInBytes <span class="operator">-</span> <span class="number">1</span> <span class="operator">+</span> maxlen <span class="operator">-</span> m_position) <span class="operator">/</span>
m_stepSizeInBytes) <span class="operator">*</span> m_stepSizeInBytes;
<span class="keyword">break</span>;
}
m_position <span class="operator">+</span><span class="operator">=</span> m_stepSizeInBytes;
}
m_position <span class="operator">-</span><span class="operator">=</span> maxlen;
<span class="keyword">return</span> maxlen;
}
<span class="comment">/**
* Interprets ptr as a pointer to int value and returns it.
*/</span>
<span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span> VoiceAnalyzer<span class="operator">::</span>getValueInt16(<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#uchar-typedef">uchar</a></span> <span class="operator">*</span>ptr)
{
<span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span> realValue <span class="operator">=</span> <span class="number">0</span>;
<span class="keyword">if</span> (m_format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>)
{
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span> value <span class="operator">=</span> <span class="operator">*</span><span class="keyword">reinterpret_cast</span><span class="operator"><</span><span class="keyword">const</span> <span class="type"><a href="qtglobal.html#quint8-typedef">quint8</a></span><span class="operator">*</span><span class="operator">></span>(ptr);
<span class="keyword">if</span> (m_format<span class="operator">.</span>sampleType() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>UnSignedInt) {
realValue <span class="operator">=</span> value <span class="operator">-</span> M_MAX_AMPLITUDE_8BIT_SIGNED <span class="operator">-</span> <span class="number">1</span>;
} <span class="keyword">else</span> <span class="keyword">if</span> (m_format<span class="operator">.</span>sampleType() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>SignedInt) {
realValue <span class="operator">=</span> value;
}
} <span class="keyword">else</span> <span class="keyword">if</span> (m_format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>) {
<span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span> value <span class="operator">=</span> <span class="number">0</span>;
<span class="keyword">if</span> (m_format<span class="operator">.</span>byteOrder() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>LittleEndian)
value <span class="operator">=</span> <a href="qtendian.html#qFromLittleEndian">qFromLittleEndian</a><span class="operator"><</span><span class="type"><a href="qtglobal.html#quint16-typedef">quint16</a></span><span class="operator">></span>(ptr);
<span class="keyword">else</span>
value <span class="operator">=</span> <a href="qtendian.html#qFromBigEndian">qFromBigEndian</a><span class="operator"><</span><span class="type"><a href="qtglobal.html#quint16-typedef">quint16</a></span><span class="operator">></span>(ptr);
<span class="keyword">if</span> (m_format<span class="operator">.</span>sampleType() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>UnSignedInt) {
realValue <span class="operator">=</span> value <span class="operator">-</span> M_MAX_AMPLITUDE_16BIT_SIGNED;
} <span class="keyword">else</span> <span class="keyword">if</span> (m_format<span class="operator">.</span>sampleType() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>SignedInt) {
realValue <span class="operator">=</span> value;
}
}
<span class="keyword">return</span> realValue;
}
<span class="comment">/**
* Takes a number between 0 and 1, scales it with CutOffScaler,
* multiplies it with maximum density, and then gives it
* to the fft helper.
*/</span>
<span class="type">void</span> VoiceAnalyzer<span class="operator">::</span>setCutOffPercentage(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> cutoff)
{
cutoff <span class="operator">=</span> CutOffScaler<span class="operator">*</span>cutoff;
<span class="keyword">if</span> (m_format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>) {
<span class="type">float</span> t <span class="operator">=</span> cutoff<span class="operator">*</span>m_totalSampleCount<span class="operator">*</span>M_MAX_AMPLITUDE_8BIT_SIGNED;
m_fftHelper<span class="operator">-</span><span class="operator">></span>setCutOffForDensity(t);
}
<span class="keyword">else</span> <span class="keyword">if</span> (m_format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>) {
<span class="type">float</span> t <span class="operator">=</span> cutoff<span class="operator">*</span>m_totalSampleCount<span class="operator">*</span>M_MAX_AMPLITUDE_16BIT_SIGNED;
m_fftHelper<span class="operator">-</span><span class="operator">></span>setCutOffForDensity(t);
}
}
<span class="comment">/**
* Returns the current target frequency.
*/</span>
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> VoiceAnalyzer<span class="operator">::</span>frequency()
{
<span class="keyword">return</span> m_frequency;
}
<span class="comment">/**
* Returns the maximum absolute value sent by
* the voiceDifference() signal.
*/</span>
<span class="type">int</span> VoiceAnalyzer<span class="operator">::</span>getMaximumVoiceDifference()
{
<span class="keyword">return</span> m_maximumVoiceDifference;
}
<span class="comment">/**
* Returns the maximum precision per note
* near the target frequency.
*/</span>
<span class="type">int</span> VoiceAnalyzer<span class="operator">::</span>getMaximumPrecisionPerNote()
{
<span class="keyword">return</span> PrecisionPerNote;
}
<span class="comment">/**
* Analyzes the voice frequency and emits appropriate signals.
*/</span>
<span class="type">void</span> VoiceAnalyzer<span class="operator">::</span>analyzeVoice()
{
m_fftHelper<span class="operator">-</span><span class="operator">></span>calculateFFT(m_samples);
<span class="type">int</span> index <span class="operator">=</span> m_fftHelper<span class="operator">-</span><span class="operator">></span>getMaximumDensityIndex();
<span class="comment">// If index == -1</span>
<span class="keyword">if</span> (index <span class="operator">=</span><span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>) {
<span class="comment">// The voice is to be filtered away.</span>
<span class="comment">// Emit the lowVoice signal and return.</span>
<span class="keyword">emit</span> lowVoice();
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"low voice"</span>;
<span class="keyword">return</span>;
}
<span class="comment">// Else, continue</span>
<span class="comment">// Let the correctIndex to be</span>
<span class="comment">// the nearest index corresponding to the correct frequency.</span>
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> stepSizeInFrequency <span class="operator">=</span> (<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>)m_format<span class="operator">.</span>sampleRate()
<span class="operator">/</span> (m_totalSampleCount <span class="operator">*</span> m_stepSize);
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> newFrequency <span class="operator">=</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(index) <span class="operator">*</span> stepSizeInFrequency;
<span class="comment">// Calculate the nearest index corresponding to the correct frequency.</span>
<span class="type">int</span> correctIndex <span class="operator">=</span> <a href="qtglobal.html#qRound">qRound</a>(m_frequency <span class="operator">/</span> stepSizeInFrequency);
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> value <span class="operator">=</span> <span class="number">0</span>;
<span class="comment">// If the obtained frequency is more than</span>
<span class="comment">// log_2(TargetFrequencyParameter) octaves less than the m_frequency:</span>
<span class="comment">// Note:</span>
<span class="comment">// Instead of m_frequency/TargetFrequencyParameter > newFrequency,</span>
<span class="comment">// the comparison is done without a div instructions by</span>
<span class="comment">// m_frequency > newFrequency * TargetFrequencyParameter.</span>
<span class="keyword">if</span> (m_frequency <span class="operator">></span> newFrequency <span class="operator">*</span> TargetFrequencyParameter) {
<span class="comment">// Set the difference value to be -m_maximumVoiceDifference.</span>
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"compare"</span> <span class="operator"><</span><span class="operator"><</span> <span class="string">"low"</span> <span class="operator"><</span><span class="operator"><</span> newFrequency <span class="operator"><</span><span class="operator"><</span> m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex <span class="operator"><</span><span class="operator"><</span> (m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex) <span class="operator">/</span> stepSizeInFrequency;
value <span class="operator">=</span> <span class="operator">-</span>m_maximumVoiceDifference;
}
<span class="comment">// Else, if the obtained frequency is more than</span>
<span class="comment">// log_2(TargetFrequencyParameter) octaves more than the m_frequency:</span>
<span class="keyword">else</span> <span class="keyword">if</span> (m_frequency<span class="operator">*</span>TargetFrequencyParameter <span class="operator"><</span> newFrequency) {
<span class="comment">// Set the difference value to be m_maximumVoiceDifference.</span>
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"compare"</span> <span class="operator"><</span><span class="operator"><</span> <span class="string">"high"</span> <span class="operator"><</span><span class="operator"><</span> newFrequency <span class="operator"><</span><span class="operator"><</span> m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex <span class="operator"><</span><span class="operator"><</span> (m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex) <span class="operator">/</span> stepSizeInFrequency;
value <span class="operator">=</span> m_maximumVoiceDifference;
}
<span class="comment">// Else:</span>
<span class="keyword">else</span> {
<span class="comment">// Calculate the difference between the obtained and the correct</span>
<span class="comment">// frequency in tones.</span>
<span class="comment">// Use stepSizeInFrequency * correctIndex instead of</span>
<span class="comment">// m_frequency so that the value is zero when there is correct</span>
<span class="comment">// voice obtained. Set the difference value to be</span>
<span class="comment">// log(frequency / target frequency) * 12 / log(2).</span>
value <span class="operator">=</span> log(newFrequency <span class="operator">/</span> (stepSizeInFrequency <span class="operator">*</span> correctIndex))
<span class="operator">*</span> <span class="number">12</span> <span class="operator">/</span> M_LN2;
<a href="qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"compare"</span> <span class="operator"><</span><span class="operator"><</span> value <span class="operator"><</span><span class="operator"><</span> newFrequency <span class="operator"><</span><span class="operator"><</span> m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex <span class="operator"><</span><span class="operator"><</span> (m_frequency <span class="operator">-</span> stepSizeInFrequency <span class="operator">*</span> correctIndex) <span class="operator">/</span> stepSizeInFrequency;
}
<span class="comment">// Emit voiceDifference signal.</span>
<span class="type"><a href="qvariant.html">QVariant</a></span> valueVar(value); <span class="comment">//Has to be QVariant for QML</span>
<span class="keyword">emit</span> voiceDifference(valueVar);
<span class="comment">// If the correctIndex is index, emit the correctFrequency signal.</span>
<span class="keyword">if</span> (correctIndex <span class="operator">=</span><span class="operator">=</span> index) {
<span class="keyword">emit</span>(correctFrequency());
}
}
<span class="comment">/**
* Empty implementation for readData, since no data is provided
* by the VoiceAnalyzer class.
*/</span>
<span class="type"><a href="qtglobal.html#qint64-typedef">qint64</a></span> VoiceAnalyzer<span class="operator">::</span>readData(<span class="type">char</span> <span class="operator">*</span>data<span class="operator">,</span> <span class="type"><a href="qtglobal.html#qint64-typedef">qint64</a></span> maxlen)
{
Q_UNUSED(data);
Q_UNUSED(maxlen);
<span class="keyword">return</span> <span class="number">0</span>;
}</pre>
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<!-- @@@demos/mobile/guitartuner/src/voiceanalyzer.cpp -->
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