Add spectrum analyzer demo app

This application is a demo which uses the QtMultimedia APIs to
capture and play back PCM audio.  While either recording or playback
is ongoing, the application performs real-time level and frequency
spectrum analysis.

Reviewed-by: Alessandro Portale

1 files changed, 107 insertions, 0 deletions

diff --git a/demos/spectrum/app/utils.h b/demos/spectrum/app/utils.h
new file mode 100644
index 0000000..cfa3633
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+++ b/demos/spectrum/app/utils.h
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+/****************************************************************************
+**
+** 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.
+**
+** 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.
+**
+*****************************************************************************/
+
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <QtCore/qglobal.h>
+#include <QDebug>
+
+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