<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>spectrumanalyser.cpp Example File | Qt Multimedia 5.12.2</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.12</td><td ><a href="qtmultimedia-index.html">Qt Multimedia</a></td><td ><a href="qtmultimedia-multimedia-spectrum-example.html">Spectrum Example</a></td><td >spectrumanalyser.cpp Example File</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtmultimedia-index.html">Qt 5.12.2 Reference Documentation</a></td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"><div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">spectrumanalyser.cpp Example File</h1> <span class="subtitle">multimedia/spectrum/app/spectrumanalyser.cpp</span> <!-- $$$multimedia/spectrum/app/spectrumanalyser.cpp-description --> <div class="descr"> <a name="details"></a> <pre class="cpp"> <span class="comment">/**************************************************************************** ** ** Copyright (C) 2017 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:BSD$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and The Qt Company. For licensing terms ** and conditions see https://www.qt.io/terms-conditions. For further ** information use the contact form at https://www.qt.io/contact-us. ** ** BSD License Usage ** Alternatively, 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 "spectrumanalyser.h"</span> <span class="preprocessor">#include "utils.h"</span> <span class="preprocessor">#include "fftreal_wrapper.h"</span> <span class="preprocessor">#include <qmath.h></span> <span class="preprocessor">#include <qmetatype.h></span> <span class="preprocessor">#include <QAudioFormat></span> <span class="preprocessor">#include <QThread></span> SpectrumAnalyserThread<span class="operator">::</span>SpectrumAnalyserThread(<span class="type">QObject</span> <span class="operator">*</span>parent) : <span class="type">QObject</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">QThread</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">></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"><</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> qCos((<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">QByteArray</span> <span class="operator">&</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"><</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i) { <span class="keyword">const</span> <span class="type">qint16</span> pcmSample <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">qint16</span><span class="operator">*</span><span class="operator">></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">></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"><</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">qreal</span>(i <span class="operator">*</span> inputFrequency) <span class="operator">/</span> (m_numSamples); <span class="keyword">const</span> <span class="type">qreal</span> real <span class="operator">=</span> m_output<span class="operator">[</span>i<span class="operator">]</span>; <span class="type">qreal</span> imag <span class="operator">=</span> <span class="number">0.0</span>; <span class="keyword">if</span> (i<span class="operator">></span><span class="number">0</span> <span class="operator">&</span><span class="operator">&</span> i<span class="operator"><</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">qreal</span> magnitude <span class="operator">=</span> qSqrt(real<span class="operator">*</span>real <span class="operator">+</span> imag<span class="operator">*</span>imag); <span class="type">qreal</span> amplitude <span class="operator">=</span> SpectrumAnalyserMultiplier <span class="operator">*</span> qLn(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">></span> <span class="number">1.0</span>); amplitude <span class="operator">=</span> qMax(<span class="type">qreal</span>(<span class="number">0.0</span>)<span class="operator">,</span> amplitude); amplitude <span class="operator">=</span> qMin(<span class="type">qreal</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">QObject</span> <span class="operator">*</span>parent) : <span class="type">QObject</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> { connect(m_thread<span class="operator">,</span> <span class="operator">&</span>SpectrumAnalyserThread<span class="operator">::</span>calculationComplete<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>SpectrumAnalyser<span class="operator">::</span>calculationComplete); } 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">QString</span> <span class="operator">&</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">"spectrum.txt"</span>)); m_textFile<span class="operator">.</span>open(<span class="type">QIODevice</span><span class="operator">::</span>WriteOnly <span class="operator">|</span> <span class="type">QIODevice</span><span class="operator">::</span>Text); m_textStream<span class="operator">.</span>setDevice(<span class="operator">&</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> bool b <span class="operator">=</span> <span class="type">QMetaObject</span><span class="operator">::</span>invokeMethod(m_thread<span class="operator">,</span> <span class="string">"setWindowFunction"</span><span class="operator">,</span> <span class="type">Qt</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">QByteArray</span> <span class="operator">&</span>buffer<span class="operator">,</span> <span class="keyword">const</span> <span class="type">QAudioFormat</span> <span class="operator">&</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"><</span><span class="operator"><</span> <span class="string">"SpectrumAnalyser::calculate"</span> <span class="operator"><</span><span class="operator"><</span> <span class="type">QThread</span><span class="operator">::</span>currentThread() <span class="operator"><</span><span class="operator"><</span> <span class="string">"state"</span> <span class="operator"><</span><span class="operator"><</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>channelCount() <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">QString</span> pcmFileName <span class="operator">=</span> m_outputDir<span class="operator">.</span>filePath(<span class="type">QString</span>(<span class="string">"spectrum_%1.pcm"</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">QChar</span>(<span class="char">'0'</span>))); <span class="type">QFile</span> pcmFile(pcmFileName); pcmFile<span class="operator">.</span>open(<span class="type">QIODevice</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"><</span><span class="operator"><</span> <span class="string">"TimeDomain "</span> <span class="operator"><</span><span class="operator"><</span> m_count <span class="operator"><</span><span class="operator"><</span> <span class="string">"\n"</span>; <span class="keyword">const</span> <span class="type">qint16</span><span class="operator">*</span> input <span class="operator">=</span> <span class="keyword">reinterpret_cast</span><span class="operator"><</span><span class="keyword">const</span> <span class="type">qint16</span><span class="operator">*</span><span class="operator">></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"><</span>m_numSamples; <span class="operator">+</span><span class="operator">+</span>i) { m_textStream <span class="operator"><</span><span class="operator"><</span> i <span class="operator"><</span><span class="operator"><</span> <span class="string">"\t"</span> <span class="operator"><</span><span class="operator"><</span> <span class="operator">*</span>input <span class="operator"><</span><span class="operator"><</span> <span class="string">"\n"</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> bool b <span class="operator">=</span> <span class="type">QMetaObject</span><span class="operator">::</span>invokeMethod(m_thread<span class="operator">,</span> <span class="string">"calculateSpectrum"</span><span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>AutoConnection<span class="operator">,</span> Q_ARG(<span class="type">QByteArray</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>sampleRate())<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"><</span><span class="operator"><</span> <span class="string">"FrequencySpectrum "</span> <span class="operator"><</span><span class="operator"><</span> m_count <span class="operator"><</span><span class="operator"><</span> <span class="string">"\n"</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"><</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"><</span><span class="operator"><</span> i <span class="operator"><</span><span class="operator"><</span> <span class="string">"\t"</span> <span class="operator"><</span><span class="operator"><</span> x<span class="operator">-</span><span class="operator">></span>frequency <span class="operator"><</span><span class="operator"><</span> <span class="string">"\t"</span> <span class="operator"><</span><span class="operator"><</span> x<span class="operator">-</span><span class="operator">></span>amplitude<span class="operator"><</span><span class="operator"><</span> <span class="string">"\t"</span> <span class="operator"><</span><span class="operator"><</span> x<span class="operator">-</span><span class="operator">></span>phase <span class="operator"><</span><span class="operator"><</span> <span class="string">"\n"</span>; <span class="preprocessor">#endif</span> } } bool 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">&</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> <!-- @@@multimedia/spectrum/app/spectrumanalyser.cpp --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br/> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br/> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>