Qt Reference Documentation

spectrum.h Example File

demos/spectrum/app/spectrum.h
 /****************************************************************************
 **
 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 ** All rights reserved.
 ** Contact: Nokia Corporation (qt-info@nokia.com)
 **
 ** 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:
 **
 ** "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 Nokia Corporation and its Subsidiary(-ies) 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."
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #ifndef SPECTRUM_H
 #define SPECTRUM_H

 #include <QtCore/qglobal.h>
 #include "utils.h"
 #include "fftreal_wrapper.h" // For FFTLengthPowerOfTwo

 //-----------------------------------------------------------------------------
 // Constants
 //-----------------------------------------------------------------------------

 // Number of audio samples used to calculate the frequency spectrum
 const int    SpectrumLengthSamples  = PowerOfTwo<FFTLengthPowerOfTwo>::Result;

 // Number of bands in the frequency spectrum
 const int    SpectrumNumBands       = 10;

 // Lower bound of first band in the spectrum
 const qreal  SpectrumLowFreq        = 0.0; // Hz

 // Upper band of last band in the spectrum
 const qreal  SpectrumHighFreq       = 1000.0; // Hz

 // Waveform window size in microseconds
 const qint64 WaveformWindowDuration = 500 * 1000;

 // Length of waveform tiles in bytes
 // Ideally, these would match the QAudio*::bufferSize(), but that isn't
 // available until some time after QAudio*::start() has been called, and we
 // need this value in order to initialize the waveform display.
 // We therefore just choose a sensible value.
 const int   WaveformTileLength      = 4096;

 // Fudge factor used to calculate the spectrum bar heights
 const qreal SpectrumAnalyserMultiplier = 0.15;

 // Disable message timeout
 const int   NullMessageTimeout      = -1;

 //-----------------------------------------------------------------------------
 // Types and data structures
 //-----------------------------------------------------------------------------

 enum WindowFunction {
     NoWindow,
     HannWindow
 };

 const WindowFunction DefaultWindowFunction = HannWindow;

 struct Tone {
     Tone(qreal freq = 0.0, qreal amp = 0.0)
     :   frequency(freq), amplitude(amp)
     { }

     // Start and end frequencies for swept tone generation
     qreal   frequency;

     // Amplitude in range [0.0, 1.0]
     qreal   amplitude;
 };

 struct SweptTone {
     SweptTone(qreal start = 0.0, qreal end = 0.0, qreal amp = 0.0)
     :   startFreq(start), endFreq(end), amplitude(amp)
     { Q_ASSERT(end >= start); }

     SweptTone(const Tone &tone)
     :   startFreq(tone.frequency), endFreq(tone.frequency), amplitude(tone.amplitude)
     { }

     // Start and end frequencies for swept tone generation
     qreal   startFreq;
     qreal   endFreq;

     // Amplitude in range [0.0, 1.0]
     qreal   amplitude;
 };

 //-----------------------------------------------------------------------------
 // Macros
 //-----------------------------------------------------------------------------

 // Macro which connects a signal to a slot, and which causes application to
 // abort if the connection fails.  This is intended to catch programming errors
 // such as mis-typing a signal or slot name.  It is necessary to write our own
 // macro to do this - the following idiom
 //     Q_ASSERT(connect(source, signal, receiver, slot));
 // will not work because Q_ASSERT compiles to a no-op in release builds.

 #define CHECKED_CONNECT(source, signal, receiver, slot) \
     if(!connect(source, signal, receiver, slot)) \
         qt_assert_x(Q_FUNC_INFO, "CHECKED_CONNECT failed", __FILE__, __LINE__);

 // Handle some dependencies between macros defined in the .pro file

 #ifdef DISABLE_WAVEFORM
 #undef SUPERIMPOSE_PROGRESS_ON_WAVEFORM
 #endif

 #endif // SPECTRUM_H
X

Thank you for giving your feedback.

Make sure it is related to this specific page. For more general bugs and requests, please use the Qt Bug Tracker.