- Qt 5.5
- Qt Multimedia
- Spectrum Example
- utils.h Example File
- Qt 5.5.1 Reference Documentation

# utils.h Example File

spectrum/app/utils.h

    /****************************************************************************
    **
    ** 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:
    **
    ** "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
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    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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    ****************************************************************************/

    #ifndef UTILS_H
    #define UTILS_H

    #include <QtCore/qglobal.h>
    #include <QDebug>

    QT_FORWARD_DECLARE_CLASS(QAudioFormat)

    //-----------------------------------------------------------------------------
    // Miscellaneous utility functions
    //-----------------------------------------------------------------------------

    qint64 audioDuration(const QAudioFormat &format, qint64 bytes);
    qint64 audioLength(const QAudioFormat &format, qint64 microSeconds);

    QString formatToString(const QAudioFormat &format);

    qreal nyquistFrequency(const QAudioFormat &format);

    // Scale PCM value to [-1.0, 1.0]
    qreal pcmToReal(qint16 pcm);

    // Scale real value in [-1.0, 1.0] to PCM
    qint16 realToPcm(qreal real);

    // Check whether the audio format is PCM
    bool isPCM(const QAudioFormat &format);

    // Check whether the audio format is signed, little-endian, 16-bit PCM
    bool isPCMS16LE(const QAudioFormat &format);

    // Compile-time calculation of powers of two

    template<int N> class PowerOfTwo
    { public: static const int Result = PowerOfTwo<N-1>::Result * 2; };

    template<> class PowerOfTwo<0>
    { public: static const int Result = 1; };

    //-----------------------------------------------------------------------------
    // Debug output
    //-----------------------------------------------------------------------------

    class NullDebug
    {
    public:
        template <typename T>
        NullDebug& operator<<(const T&) { return *this; }
    };

    inline NullDebug nullDebug() { return NullDebug(); }

    #ifdef LOG_ENGINE
    #   define ENGINE_DEBUG qDebug()
    #else
    #   define ENGINE_DEBUG nullDebug()
    #endif

    #ifdef LOG_SPECTRUMANALYSER
    #   define SPECTRUMANALYSER_DEBUG qDebug()
    #else
    #   define SPECTRUMANALYSER_DEBUG nullDebug()
    #endif

    #ifdef LOG_WAVEFORM
    #   define WAVEFORM_DEBUG qDebug()
    #else
    #   define WAVEFORM_DEBUG nullDebug()
    #endif

    #endif // UTILS_H