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<h1 class="title">spectrumanalyser.cpp Example File</h1>
<span class="small-subtitle">demos/spectrum/app/spectrumanalyser.cpp</span>
<!-- $$$demos/spectrum/app/spectrumanalyser.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 examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** &quot;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
** &quot;AS IS&quot; 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.&quot;
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include &quot;spectrumanalyser.h&quot;</span>
<span class="preprocessor">#include &quot;utils.h&quot;</span>
<span class="preprocessor">#include &lt;QtCore/qmath.h&gt;</span>
<span class="preprocessor">#include &lt;QtCore/qmetatype.h&gt;</span>
<span class="preprocessor">#include &lt;QtMultimedia/QAudioFormat&gt;</span>
<span class="preprocessor">#include &lt;QThread&gt;</span>
<span class="preprocessor">#include &quot;fftreal_wrapper.h&quot;</span>
SpectrumAnalyserThread<span class="operator">::</span>SpectrumAnalyserThread(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent)
: <span class="type"><a href="qobject.html">QObject</a></span>(parent)
<span class="preprocessor">#ifndef DISABLE_FFT</span>
<span class="operator">,</span> m_fft(<span class="keyword">new</span> FFTRealWrapper)
<span class="preprocessor">#endif</span>
<span class="operator">,</span> m_numSamples(SpectrumLengthSamples)
<span class="operator">,</span> m_windowFunction(DefaultWindowFunction)
<span class="operator">,</span> m_window(SpectrumLengthSamples<span class="operator">,</span> <span class="number">0.0</span>)
<span class="operator">,</span> m_input(SpectrumLengthSamples<span class="operator">,</span> <span class="number">0.0</span>)
<span class="operator">,</span> m_output(SpectrumLengthSamples<span class="operator">,</span> <span class="number">0.0</span>)
<span class="operator">,</span> m_spectrum(SpectrumLengthSamples)
<span class="preprocessor">#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD</span>
<span class="operator">,</span> m_thread(<span class="keyword">new</span> <span class="type"><a href="qthread.html">QThread</a></span>(<span class="keyword">this</span>))
<span class="preprocessor">#endif</span>
{
<span class="preprocessor">#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD</span>
<span class="comment">// moveToThread() cannot be called on a QObject with a parent</span>
setParent(<span class="number">0</span>);
moveToThread(m_thread);
m_thread<span class="operator">-</span><span class="operator">&gt;</span>start();
<span class="preprocessor">#endif</span>
calculateWindow();
}
SpectrumAnalyserThread<span class="operator">::</span><span class="operator">~</span>SpectrumAnalyserThread()
{
<span class="preprocessor">#ifndef DISABLE_FFT</span>
<span class="keyword">delete</span> m_fft;
<span class="preprocessor">#endif</span>
}
<span class="type">void</span> SpectrumAnalyserThread<span class="operator">::</span>setWindowFunction(WindowFunction type)
{
m_windowFunction <span class="operator">=</span> type;
calculateWindow();
}
<span class="type">void</span> SpectrumAnalyserThread<span class="operator">::</span>calculateWindow()
{
<span class="keyword">for</span> (<span class="type">int</span> i<span class="operator">=</span><span class="number">0</span>; i<span class="operator">&lt;</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i) {
DataType x <span class="operator">=</span> <span class="number">0.0</span>;
<span class="keyword">switch</span> (m_windowFunction) {
<span class="keyword">case</span> NoWindow:
x <span class="operator">=</span> <span class="number">1.0</span>;
<span class="keyword">break</span>;
<span class="keyword">case</span> HannWindow:
x <span class="operator">=</span> <span class="number">0.5</span> <span class="operator">*</span> (<span class="number">1</span> <span class="operator">-</span> <a href="qtcore-qmath-h.html#qCos">qCos</a>((<span class="number">2</span> <span class="operator">*</span> M_PI <span class="operator">*</span> i) <span class="operator">/</span> (m_numSamples <span class="operator">-</span> <span class="number">1</span>)));
<span class="keyword">break</span>;
<span class="keyword">default</span>:
Q_ASSERT(<span class="keyword">false</span>);
}
m_window<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">=</span> x;
}
}
<span class="type">void</span> SpectrumAnalyserThread<span class="operator">::</span>calculateSpectrum(<span class="keyword">const</span> <span class="type"><a href="qbytearray.html">QByteArray</a></span> <span class="operator">&amp;</span>buffer<span class="operator">,</span>
<span class="type">int</span> inputFrequency<span class="operator">,</span>
<span class="type">int</span> bytesPerSample)
{
<span class="preprocessor">#ifndef DISABLE_FFT</span>
Q_ASSERT(buffer<span class="operator">.</span>size() <span class="operator">=</span><span class="operator">=</span> m_numSamples <span class="operator">*</span> bytesPerSample);
<span class="comment">// Initialize data array</span>
<span class="keyword">const</span> <span class="type">char</span> <span class="operator">*</span>ptr <span class="operator">=</span> buffer<span class="operator">.</span>constData();
<span class="keyword">for</span> (<span class="type">int</span> i<span class="operator">=</span><span class="number">0</span>; i<span class="operator">&lt;</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i) {
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span> pcmSample <span class="operator">=</span> <span class="operator">*</span><span class="keyword">reinterpret_cast</span><span class="operator">&lt;</span><span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span><span class="operator">*</span><span class="operator">&gt;</span>(ptr);
<span class="comment">// Scale down to range [-1.0, 1.0]</span>
<span class="keyword">const</span> DataType realSample <span class="operator">=</span> pcmToReal(pcmSample);
<span class="keyword">const</span> DataType windowedSample <span class="operator">=</span> realSample <span class="operator">*</span> m_window<span class="operator">[</span>i<span class="operator">]</span>;
m_input<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">=</span> windowedSample;
ptr <span class="operator">+</span><span class="operator">=</span> bytesPerSample;
}
<span class="comment">// Calculate the FFT</span>
m_fft<span class="operator">-</span><span class="operator">&gt;</span>calculateFFT(m_output<span class="operator">.</span>data()<span class="operator">,</span> m_input<span class="operator">.</span>data());
<span class="comment">// Analyze output to obtain amplitude and phase for each frequency</span>
<span class="keyword">for</span> (<span class="type">int</span> i<span class="operator">=</span><span class="number">2</span>; i<span class="operator">&lt;</span><span class="operator">=</span>m_numSamples<span class="operator">/</span><span class="number">2</span>; <span class="operator">+</span><span class="operator">+</span>i) {
<span class="comment">// Calculate frequency of this complex sample</span>
m_spectrum<span class="operator">[</span>i<span class="operator">]</span><span class="operator">.</span>frequency <span class="operator">=</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(i <span class="operator">*</span> inputFrequency) <span class="operator">/</span> (m_numSamples);
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> real <span class="operator">=</span> m_output<span class="operator">[</span>i<span class="operator">]</span>;
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> imag <span class="operator">=</span> <span class="number">0.0</span>;
<span class="keyword">if</span> (i<span class="operator">&gt;</span><span class="number">0</span> <span class="operator">&amp;</span><span class="operator">&amp;</span> i<span class="operator">&lt;</span>m_numSamples<span class="operator">/</span><span class="number">2</span>)
imag <span class="operator">=</span> m_output<span class="operator">[</span>m_numSamples<span class="operator">/</span><span class="number">2</span> <span class="operator">+</span> i<span class="operator">]</span>;
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> magnitude <span class="operator">=</span> sqrt(real<span class="operator">*</span>real <span class="operator">+</span> imag<span class="operator">*</span>imag);
<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span> amplitude <span class="operator">=</span> SpectrumAnalyserMultiplier <span class="operator">*</span> log(magnitude);
<span class="comment">// Bound amplitude to [0.0, 1.0]</span>
m_spectrum<span class="operator">[</span>i<span class="operator">]</span><span class="operator">.</span>clipped <span class="operator">=</span> (amplitude <span class="operator">&gt;</span> <span class="number">1.0</span>);
amplitude <span class="operator">=</span> <a href="qtglobal.html#qMax">qMax</a>(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(<span class="number">0.0</span>)<span class="operator">,</span> amplitude);
amplitude <span class="operator">=</span> <a href="qtglobal.html#qMin">qMin</a>(<span class="type"><a href="qtglobal.html#qreal-typedef">qreal</a></span>(<span class="number">1.0</span>)<span class="operator">,</span> amplitude);
m_spectrum<span class="operator">[</span>i<span class="operator">]</span><span class="operator">.</span>amplitude <span class="operator">=</span> amplitude;
}
<span class="preprocessor">#endif</span>
<span class="keyword">emit</span> calculationComplete(m_spectrum);
}
<span class="comment">//=============================================================================</span>
<span class="comment">// SpectrumAnalyser</span>
<span class="comment">//=============================================================================</span>
SpectrumAnalyser<span class="operator">::</span>SpectrumAnalyser(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent)
: <span class="type"><a href="qobject.html">QObject</a></span>(parent)
<span class="operator">,</span> m_thread(<span class="keyword">new</span> SpectrumAnalyserThread(<span class="keyword">this</span>))
<span class="operator">,</span> m_state(Idle)
<span class="preprocessor">#ifdef DUMP_SPECTRUMANALYSER</span>
<span class="operator">,</span> m_count(<span class="number">0</span>)
<span class="preprocessor">#endif</span>
{
CHECKED_CONNECT(m_thread<span class="operator">,</span> SIGNAL(calculationComplete(FrequencySpectrum))<span class="operator">,</span>
<span class="keyword">this</span><span class="operator">,</span> SLOT(calculationComplete(FrequencySpectrum)));
}
SpectrumAnalyser<span class="operator">::</span><span class="operator">~</span>SpectrumAnalyser()
{
}
<span class="preprocessor">#ifdef DUMP_SPECTRUMANALYSER</span>
<span class="type">void</span> SpectrumAnalyser<span class="operator">::</span>setOutputPath(<span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&amp;</span>outputDir)
{
m_outputDir<span class="operator">.</span>setPath(outputDir);
m_textFile<span class="operator">.</span>setFileName(m_outputDir<span class="operator">.</span>filePath(<span class="string">&quot;spectrum.txt&quot;</span>));
m_textFile<span class="operator">.</span>open(<span class="type"><a href="qiodevice.html">QIODevice</a></span><span class="operator">::</span>WriteOnly <span class="operator">|</span> <span class="type"><a href="qiodevice.html">QIODevice</a></span><span class="operator">::</span>Text);
m_textStream<span class="operator">.</span>setDevice(<span class="operator">&amp;</span>m_textFile);
}
<span class="preprocessor">#endif</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Public functions</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="type">void</span> SpectrumAnalyser<span class="operator">::</span>setWindowFunction(WindowFunction type)
{
<span class="keyword">const</span> <span class="type">bool</span> b <span class="operator">=</span> <span class="type"><a href="qmetaobject.html">QMetaObject</a></span><span class="operator">::</span>invokeMethod(m_thread<span class="operator">,</span> <span class="string">&quot;setWindowFunction&quot;</span><span class="operator">,</span>
<span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>AutoConnection<span class="operator">,</span>
Q_ARG(WindowFunction<span class="operator">,</span> type));
Q_ASSERT(b);
Q_UNUSED(b) <span class="comment">// suppress warnings in release builds</span>
}
<span class="type">void</span> SpectrumAnalyser<span class="operator">::</span>calculate(<span class="keyword">const</span> <span class="type"><a href="qbytearray.html">QByteArray</a></span> <span class="operator">&amp;</span>buffer<span class="operator">,</span>
<span class="keyword">const</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span> <span class="operator">&amp;</span>format)
{
<span class="comment">// QThread::currentThread is marked 'for internal use only', but</span>
<span class="comment">// we're only using it for debug output here, so it's probably OK :)</span>
SPECTRUMANALYSER_DEBUG <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;SpectrumAnalyser::calculate&quot;</span>
<span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="type"><a href="qthread.html">QThread</a></span><span class="operator">::</span>currentThread()
<span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;state&quot;</span> <span class="operator">&lt;</span><span class="operator">&lt;</span> m_state;
<span class="keyword">if</span> (isReady()) {
Q_ASSERT(isPCMS16LE(format));
<span class="keyword">const</span> <span class="type">int</span> bytesPerSample <span class="operator">=</span> format<span class="operator">.</span>sampleSize() <span class="operator">*</span> format<span class="operator">.</span>channels() <span class="operator">/</span> <span class="number">8</span>;
<span class="preprocessor">#ifdef DUMP_SPECTRUMANALYSER</span>
m_count<span class="operator">+</span><span class="operator">+</span>;
<span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> pcmFileName <span class="operator">=</span> m_outputDir<span class="operator">.</span>filePath(<span class="type"><a href="qstring.html">QString</a></span>(<span class="string">&quot;spectrum_%1.pcm&quot;</span>)<span class="operator">.</span>arg(m_count<span class="operator">,</span> <span class="number">4</span><span class="operator">,</span> <span class="number">10</span><span class="operator">,</span> <span class="type"><a href="qchar.html">QChar</a></span>(<span class="char">'0'</span>)));
<span class="type"><a href="qfile.html">QFile</a></span> pcmFile(pcmFileName);
pcmFile<span class="operator">.</span>open(<span class="type"><a href="qiodevice.html">QIODevice</a></span><span class="operator">::</span>WriteOnly);
<span class="keyword">const</span> <span class="type">int</span> bufferLength <span class="operator">=</span> m_numSamples <span class="operator">*</span> bytesPerSample;
pcmFile<span class="operator">.</span>write(buffer<span class="operator">,</span> bufferLength);
m_textStream <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;TimeDomain &quot;</span> <span class="operator">&lt;</span><span class="operator">&lt;</span> m_count <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\n&quot;</span>;
<span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span><span class="operator">*</span> input <span class="operator">=</span> <span class="keyword">reinterpret_cast</span><span class="operator">&lt;</span><span class="keyword">const</span> <span class="type"><a href="qtglobal.html#qint16-typedef">qint16</a></span><span class="operator">*</span><span class="operator">&gt;</span>(buffer);
<span class="keyword">for</span> (<span class="type">int</span> i<span class="operator">=</span><span class="number">0</span>; i<span class="operator">&lt;</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i) {
m_textStream <span class="operator">&lt;</span><span class="operator">&lt;</span> i <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\t&quot;</span> <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="operator">*</span>input <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\n&quot;</span>;
input <span class="operator">+</span><span class="operator">=</span> format<span class="operator">.</span>channels();
}
<span class="preprocessor">#endif</span>
m_state <span class="operator">=</span> Busy;
<span class="comment">// Invoke SpectrumAnalyserThread::calculateSpectrum using QMetaObject. If</span>
<span class="comment">// m_thread is in a different thread from the current thread, the</span>
<span class="comment">// calculation will be done in the child thread.</span>
<span class="comment">// Once the calculation is finished, a calculationChanged signal will be</span>
<span class="comment">// emitted by m_thread.</span>
<span class="keyword">const</span> <span class="type">bool</span> b <span class="operator">=</span> <span class="type"><a href="qmetaobject.html">QMetaObject</a></span><span class="operator">::</span>invokeMethod(m_thread<span class="operator">,</span> <span class="string">&quot;calculateSpectrum&quot;</span><span class="operator">,</span>
<span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>AutoConnection<span class="operator">,</span>
Q_ARG(<span class="type"><a href="qbytearray.html">QByteArray</a></span><span class="operator">,</span> buffer)<span class="operator">,</span>
Q_ARG(<span class="type">int</span><span class="operator">,</span> format<span class="operator">.</span>frequency())<span class="operator">,</span>
Q_ARG(<span class="type">int</span><span class="operator">,</span> bytesPerSample));
Q_ASSERT(b);
Q_UNUSED(b) <span class="comment">// suppress warnings in release builds</span>
<span class="preprocessor">#ifdef DUMP_SPECTRUMANALYSER</span>
m_textStream <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;FrequencySpectrum &quot;</span> <span class="operator">&lt;</span><span class="operator">&lt;</span> m_count <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\n&quot;</span>;
FrequencySpectrum<span class="operator">::</span>const_iterator x <span class="operator">=</span> m_spectrum<span class="operator">.</span>begin();
<span class="keyword">for</span> (<span class="type">int</span> i<span class="operator">=</span><span class="number">0</span>; i<span class="operator">&lt;</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i<span class="operator">,</span> <span class="operator">+</span><span class="operator">+</span>x)
m_textStream <span class="operator">&lt;</span><span class="operator">&lt;</span> i <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\t&quot;</span>
<span class="operator">&lt;</span><span class="operator">&lt;</span> x<span class="operator">-</span><span class="operator">&gt;</span>frequency <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\t&quot;</span>
<span class="operator">&lt;</span><span class="operator">&lt;</span> x<span class="operator">-</span><span class="operator">&gt;</span>amplitude<span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\t&quot;</span>
<span class="operator">&lt;</span><span class="operator">&lt;</span> x<span class="operator">-</span><span class="operator">&gt;</span>phase <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\n&quot;</span>;
<span class="preprocessor">#endif</span>
}
}
<span class="type">bool</span> SpectrumAnalyser<span class="operator">::</span>isReady() <span class="keyword">const</span>
{
<span class="keyword">return</span> (Idle <span class="operator">=</span><span class="operator">=</span> m_state);
}
<span class="type">void</span> SpectrumAnalyser<span class="operator">::</span>cancelCalculation()
{
<span class="keyword">if</span> (Busy <span class="operator">=</span><span class="operator">=</span> m_state)
m_state <span class="operator">=</span> Cancelled;
}
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Private slots</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="type">void</span> SpectrumAnalyser<span class="operator">::</span>calculationComplete(<span class="keyword">const</span> FrequencySpectrum <span class="operator">&amp;</span>spectrum)
{
Q_ASSERT(Idle <span class="operator">!</span><span class="operator">=</span> m_state);
<span class="keyword">if</span> (Busy <span class="operator">=</span><span class="operator">=</span> m_state)
<span class="keyword">emit</span> spectrumChanged(spectrum);
m_state <span class="operator">=</span> Idle;
}</pre>
</div>
<!-- @@@demos/spectrum/app/spectrumanalyser.cpp -->
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