/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** 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 Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file.  Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \example demos/spectrum
    \title Spectrum Analyzer

    \brief The Spectrum Analyzer demo shows how the \l{QtMultimedia Module} can be
    used in Qt applications to capture and then play back an audio stream.

    \image spectrum-demo.png

    Because QtMultimedia allows the application to access the raw audio
    stream, the data can either be inspected or modified by the application.
    The Spectrum Analyzer demo displays three pieces of information while
    audio is being either captured or played back:

    \list
    \o Information about the raw audio stream, shown in the uppermost widget:
    \list
        \o The amount of data currently in the buffer, shown in blue
        \o The segment of data which was most recently analysed to compute
        the frequency spectrum, shown in green
        \o The raw audio waveform, shown in white and scrolling from right to
        left
    \endlist
    \o A representation of the frequency spectrum, shown at the lower left
    \o The current RMS level of the audio stream, and the recent 'high
    watermark' level, shown at the lower right
    \endlist

    Spectrum analysis is performed by calculating the Fast Fourier Transform
    (FFT) of a segment of audio data.  An open-source library,
    \l{http://ldesoras.free.fr/prod.html}{FFTReal}, against which the
    application is dynamically linked, is used to compute the transform.
*/