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<h1 class="title">spectrum.h Example File</h1>
<span class="subtitle">multimedia/spectrum/app/spectrum.h</span>
<!-- $$$multimedia/spectrum/app/spectrum.h-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
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** 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.
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** 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.
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<span class="preprocessor">#ifndef SPECTRUM_H</span>
<span class="preprocessor">#define SPECTRUM_H</span>
<span class="preprocessor">#include <qglobal.h></span>
<span class="preprocessor">#include "utils.h"</span>
<span class="preprocessor">#include "fftreal_wrapper.h" // For FFTLengthPowerOfTwo</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Constants</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Number of audio samples used to calculate the frequency spectrum</span>
<span class="keyword">const</span> <span class="type">int</span> SpectrumLengthSamples <span class="operator">=</span> PowerOfTwo<span class="operator"><</span>FFTLengthPowerOfTwo<span class="operator">></span><span class="operator">::</span>Result;
<span class="comment">// Number of bands in the frequency spectrum</span>
<span class="keyword">const</span> <span class="type">int</span> SpectrumNumBands <span class="operator">=</span> <span class="number">10</span>;
<span class="comment">// Lower bound of first band in the spectrum</span>
<span class="keyword">const</span> <span class="type">qreal</span> SpectrumLowFreq <span class="operator">=</span> <span class="number">0.0</span>; <span class="comment">// Hz</span>
<span class="comment">// Upper band of last band in the spectrum</span>
<span class="keyword">const</span> <span class="type">qreal</span> SpectrumHighFreq <span class="operator">=</span> <span class="number">1000.0</span>; <span class="comment">// Hz</span>
<span class="comment">// Waveform window size in microseconds</span>
<span class="keyword">const</span> <span class="type">qint64</span> WaveformWindowDuration <span class="operator">=</span> <span class="number">500</span> <span class="operator">*</span> <span class="number">1000</span>;
<span class="comment">// Length of waveform tiles in bytes</span>
<span class="comment">// Ideally, these would match the QAudio*::bufferSize(), but that isn't</span>
<span class="comment">// available until some time after QAudio*::start() has been called, and we</span>
<span class="comment">// need this value in order to initialize the waveform display.</span>
<span class="comment">// We therefore just choose a sensible value.</span>
<span class="keyword">const</span> <span class="type">int</span> WaveformTileLength <span class="operator">=</span> <span class="number">4096</span>;
<span class="comment">// Fudge factor used to calculate the spectrum bar heights</span>
<span class="keyword">const</span> <span class="type">qreal</span> SpectrumAnalyserMultiplier <span class="operator">=</span> <span class="number">0.15</span>;
<span class="comment">// Disable message timeout</span>
<span class="keyword">const</span> <span class="type">int</span> NullMessageTimeout <span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>;
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Types and data structures</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="keyword">enum</span> WindowFunction {
NoWindow<span class="operator">,</span>
HannWindow
};
<span class="keyword">const</span> WindowFunction DefaultWindowFunction <span class="operator">=</span> HannWindow;
<span class="keyword">struct</span> Tone
{
Tone(<span class="type">qreal</span> freq <span class="operator">=</span> <span class="number">0.0</span><span class="operator">,</span> <span class="type">qreal</span> amp <span class="operator">=</span> <span class="number">0.0</span>)
: frequency(freq)<span class="operator">,</span> amplitude(amp)
{ }
<span class="comment">// Start and end frequencies for swept tone generation</span>
<span class="type">qreal</span> frequency;
<span class="comment">// Amplitude in range [0.0, 1.0]</span>
<span class="type">qreal</span> amplitude;
};
<span class="keyword">struct</span> SweptTone
{
SweptTone(<span class="type">qreal</span> start <span class="operator">=</span> <span class="number">0.0</span><span class="operator">,</span> <span class="type">qreal</span> end <span class="operator">=</span> <span class="number">0.0</span><span class="operator">,</span> <span class="type">qreal</span> amp <span class="operator">=</span> <span class="number">0.0</span>)
: startFreq(start)<span class="operator">,</span> endFreq(end)<span class="operator">,</span> amplitude(amp)
{ Q_ASSERT(end <span class="operator">></span><span class="operator">=</span> start); }
SweptTone(<span class="keyword">const</span> Tone <span class="operator">&</span>tone)
: startFreq(tone<span class="operator">.</span>frequency)<span class="operator">,</span> endFreq(tone<span class="operator">.</span>frequency)<span class="operator">,</span> amplitude(tone<span class="operator">.</span>amplitude)
{ }
<span class="comment">// Start and end frequencies for swept tone generation</span>
<span class="type">qreal</span> startFreq;
<span class="type">qreal</span> endFreq;
<span class="comment">// Amplitude in range [0.0, 1.0]</span>
<span class="type">qreal</span> amplitude;
};
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Macros</span>
<span class="comment">//-----------------------------------------------------------------------------</span>
<span class="comment">// Macro which connects a signal to a slot, and which causes application to</span>
<span class="comment">// abort if the connection fails. This is intended to catch programming errors</span>
<span class="comment">// such as mis-typing a signal or slot name. It is necessary to write our own</span>
<span class="comment">// macro to do this - the following idiom</span>
<span class="comment">// Q_ASSERT(connect(source, signal, receiver, slot));</span>
<span class="comment">// will not work because Q_ASSERT compiles to a no-op in release builds.</span>
<span class="preprocessor">#define CHECKED_CONNECT(source, signal, receiver, slot) \
if (!connect(source, signal, receiver, slot)) \
qt_assert_x(Q_FUNC_INFO, "CHECKED_CONNECT failed", __FILE__, __LINE__);</span>
<span class="comment">// Handle some dependencies between macros defined in the .pro file</span>
<span class="preprocessor">#ifdef DISABLE_WAVEFORM</span>
<span class="preprocessor">#undef SUPERIMPOSE_PROGRESS_ON_WAVEFORM</span>
<span class="preprocessor">#endif</span>
<span class="preprocessor">#endif // SPECTRUM_H</span>
</pre>
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<!-- @@@multimedia/spectrum/app/spectrum.h -->
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