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, 188 insertions, 0 deletions

diff --git a/demos/spectrum/app/spectrumanalyser.h b/demos/spectrum/app/spectrumanalyser.h
new file mode 100644
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+++ b/demos/spectrum/app/spectrumanalyser.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 SPECTRUMANALYSER_H
+#define SPECTRUMANALYSER_H
+
+#include <QByteArray>
+#include <QObject>
+#include <QVector>
+
+#ifdef DUMP_SPECTRUMANALYSER
+#include <QDir>
+#include <QFile>
+#include <QTextStream>
+#endif
+
+#include "frequencyspectrum.h"
+#include "spectrum.h"
+
+#ifndef DISABLE_FFT
+#include "FFTRealFixLenParam.h"
+#endif
+
+class QAudioFormat;
+class QThread;
+class FFTRealWrapper;
+
+class SpectrumAnalyserThreadPrivate;
+
+/**
+ * Implementation of the spectrum analysis which can be run in a
+ * separate thread.
+ */
+class SpectrumAnalyserThread : public QObject
+{
+    Q_OBJECT
+public:
+    SpectrumAnalyserThread(QObject *parent);
+    ~SpectrumAnalyserThread();
+
+public slots:
+    void setWindowFunction(WindowFunction type);
+    void calculateSpectrum(const QByteArray &buffer,
+                           int inputFrequency,
+                           int bytesPerSample);
+
+signals:
+    void calculationComplete(const FrequencySpectrum &spectrum);
+
+private:
+    void calculateWindow();
+
+private:
+#ifndef DISABLE_FFT
+    FFTRealWrapper*                             m_fft;
+#endif
+
+    const int                                   m_numSamples;
+
+    WindowFunction                              m_windowFunction;
+
+#ifdef DISABLE_FFT
+    typedef qreal                               DataType;
+#else
+    typedef FFTRealFixLenParam::DataType        DataType;
+#endif
+    QVector<DataType>                           m_window;
+
+    QVector<DataType>                           m_input;
+    QVector<DataType>                           m_output;
+
+    FrequencySpectrum                           m_spectrum;
+
+#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD
+    QThread*                                    m_thread;
+#endif
+};
+
+/**
+ * Class which performs frequency spectrum analysis on a window of
+ * audio samples, provided to it by the Engine.
+ */
+class SpectrumAnalyser : public QObject
+{
+    Q_OBJECT
+public:
+    SpectrumAnalyser(QObject *parent = 0);
+    ~SpectrumAnalyser();
+
+#ifdef DUMP_SPECTRUMANALYSER
+    void setOutputPath(const QString &outputPath);
+#endif
+
+public:
+    /*
+     * Set the windowing function which is applied before calculating the FFT
+     */
+    void setWindowFunction(WindowFunction type);
+
+    /*
+     * Calculate a frequency spectrum
+     *
+     * \param buffer       Audio data
+     * \param format       Format of audio data
+     *
+     * Frequency spectrum is calculated asynchronously.  The result is returned
+     * via the spectrumChanged signal.
+     *
+     * An ongoing calculation can be cancelled by calling cancelCalculation().
+     *
+     */
+    void calculate(const QByteArray &buffer, const QAudioFormat &format);
+
+    /*
+     * Check whether the object is ready to perform another calculation
+     */
+    bool isReady() const;
+
+    /*
+     * Cancel an ongoing calculation
+     *
+     * Note that cancelling is asynchronous.
+     */
+    void cancelCalculation();
+
+signals:
+    void spectrumChanged(const FrequencySpectrum &spectrum);
+
+private slots:
+    void calculationComplete(const FrequencySpectrum &spectrum);
+
+private:
+    void calculateWindow();
+
+private:
+
+    SpectrumAnalyserThread*    m_thread;
+
+    enum State {
+        Idle,
+        Busy,
+        Cancelled
+    };
+
+    State              m_state;
+
+#ifdef DUMP_SPECTRUMANALYSER
+    QDir                m_outputDir;
+    int                 m_count;
+    QFile               m_textFile;
+    QTextStream         m_textStream;
+#endif
+};
+
+#endif // SPECTRUMANALYSER_H
+