<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en_US" lang="en_US"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Qt 4.8: voiceanalyzer.cpp Example File (demos/mobile/guitartuner/src/voiceanalyzer.cpp)</title> <link rel="stylesheet" type="text/css" href="style/style.css" /> <script src="scripts/jquery.js" type="text/javascript"></script> <script src="scripts/functions.js" type="text/javascript"></script> <link rel="stylesheet" type="text/css" href="style/superfish.css" /> <link rel="stylesheet" type="text/css" href="style/narrow.css" /> <!--[if IE]> <meta name="MSSmartTagsPreventParsing" content="true"> <meta http-equiv="imagetoolbar" content="no"> <![endif]--> <!--[if lt IE 7]> <link rel="stylesheet" type="text/css" href="style/style_ie6.css"> <![endif]--> <!--[if IE 7]> <link rel="stylesheet" type="text/css" href="style/style_ie7.css"> <![endif]--> <!--[if IE 8]> <link rel="stylesheet" type="text/css" href="style/style_ie8.css"> <![endif]--> <script src="scripts/superfish.js" type="text/javascript"></script> <script src="scripts/narrow.js" type="text/javascript"></script> </head> <body class="" onload="CheckEmptyAndLoadList();"> <div class="header" id="qtdocheader"> <div class="content"> <div id="nav-logo"> <a href="index.html">Home</a></div> <a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a> <div id="narrowsearch"></div> <div id="nav-topright"> <ul> <li class="nav-topright-home"><a href="http://qt.digia.com/">Qt HOME</a></li> <li class="nav-topright-dev"><a href="http://qt-project.org/">DEV</a></li> <li class="nav-topright-doc nav-topright-doc-active"><a href="http://qt-project.org/doc/"> DOC</a></li> <li class="nav-topright-blog"><a href="http://blog.qt.digia.com/">BLOG</a></li> </ul> </div> <div id="shortCut"> <ul> <li class="shortCut-topleft-inactive"><span><a href="index.html">Qt 4.8</a></span></li> <li class="shortCut-topleft-active"><a href="http://qt-project.org/doc/">ALL VERSIONS </a></li> </ul> </div> <ul class="sf-menu" id="narrowmenu"> <li><a href="#">API Lookup</a> <ul> <li><a href="classes.html">Class index</a></li> <li><a href="functions.html">Function index</a></li> <li><a href="modules.html">Modules</a></li> <li><a href="namespaces.html">Namespaces</a></li> <li><a href="qtglobal.html">Global Declarations</a></li> <li><a href="qdeclarativeelements.html">QML elements</a></li> </ul> </li> <li><a href="#">Qt Topics</a> <ul> <li><a href="qt-basic-concepts.html">Programming with Qt</a></li> <li><a href="qtquick.html">Device UIs & Qt Quick</a></li> <li><a href="qt-gui-concepts.html">UI Design with Qt</a></li> <li><a href="supported-platforms.html">Supported Platforms</a></li> <li><a href="technology-apis.html">Qt and Key Technologies</a></li> <li><a href="best-practices.html">How-To's and Best Practices</a></li> </ul> </li> <li><a href="#">Examples</a> <ul> <li><a href="all-examples.html">Examples</a></li> <li><a href="tutorials.html">Tutorials</a></li> <li><a href="demos.html">Demos</a></li> <li><a href="qdeclarativeexamples.html">QML Examples</a></li> </ul> </li> </ul> </div> </div> <div class="wrapper"> <div class="hd"> <span></span> </div> <div class="bd group"> <div class="sidebar"> <div class="searchlabel"> Search index:</div> <div class="search" id="sidebarsearch"> <form id="qtdocsearch" action="" onsubmit="return false;"> <fieldset> <input type="text" name="searchstring" id="pageType" value="" /> <div id="resultdialog"> <a href="#" id="resultclose">Close</a> <p id="resultlinks" class="all"><a href="#" id="showallresults">All</a> | <a href="#" id="showapiresults">API</a> | <a href="#" id="showarticleresults">Articles</a> | <a href="#" id="showexampleresults">Examples</a></p> <p id="searchcount" class="all"><span id="resultcount"></span><span id="apicount"></span><span id="articlecount"></span><span id="examplecount"></span> results:</p> <ul id="resultlist" class="all"> </ul> </div> </fieldset> </form> </div> <div class="box first bottombar" id="lookup"> <h2 title="API Lookup"><span></span> API Lookup</h2> <div id="list001" class="list"> <ul id="ul001" > <li class="defaultLink"><a href="classes.html">Class index</a></li> <li class="defaultLink"><a href="functions.html">Function index</a></li> <li class="defaultLink"><a href="modules.html">Modules</a></li> <li class="defaultLink"><a href="namespaces.html">Namespaces</a></li> <li class="defaultLink"><a href="qtglobal.html">Global Declarations</a></li> <li class="defaultLink"><a href="qdeclarativeelements.html">QML elements</a></li> </ul> </div> </div> <div class="box bottombar" id="topics"> <h2 title="Qt Topics"><span></span> Qt Topics</h2> <div id="list002" class="list"> <ul id="ul002" > <li class="defaultLink"><a href="qt-basic-concepts.html">Programming with Qt</a></li> <li class="defaultLink"><a href="qtquick.html">Device UIs & Qt Quick</a></li> <li class="defaultLink"><a href="qt-gui-concepts.html">UI Design with Qt</a></li> <li class="defaultLink"><a href="supported-platforms.html">Supported Platforms</a></li> <li class="defaultLink"><a href="technology-apis.html">Qt and Key Technologies</a></li> <li class="defaultLink"><a href="best-practices.html">How-To's and Best Practices</a></li> </ul> </div> </div> <div class="box" id="examples"> <h2 title="Examples"><span></span> Examples</h2> <div id="list003" class="list"> <ul id="ul003"> <li class="defaultLink"><a href="all-examples.html">Examples</a></li> <li class="defaultLink"><a href="tutorials.html">Tutorials</a></li> <li class="defaultLink"><a href="demos.html">Demos</a></li> <li class="defaultLink"><a href="qdeclarativeexamples.html">QML Examples</a></li> </ul> </div> </div> </div> <div class="wrap"> <div class="toolbar"> <div class="breadcrumb toolblock"> <ul> <li class="first"><a href="index.html">Home</a></li> <!-- Breadcrumbs go here --> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <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> </div> <!-- @@@demos/mobile/guitartuner/src/voiceanalyzer.cpp --> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2015 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.</p> <br /> <p> 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.</p> <p> Documentation sources may be obtained from <a href="http://www.qt-project.org"> www.qt-project.org</a>.</p> <br /> <p> 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. <a title="Privacy Policy" href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p> </div> <script src="scripts/functions.js" type="text/javascript"></script> </body> </html>