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, 309 insertions, 0 deletions

diff --git a/demos/spectrum/app/engine.h b/demos/spectrum/app/engine.h
new file mode 100644
index 0000000..7028247
--- /dev/null
+++ b/demos/spectrum/app/engine.h
@@ -0,0 +1,309 @@
+/****************************************************************************
+**
+** 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 ENGINE_H
+#define ENGINE_H
+
+#include "spectrum.h"
+#include "spectrumanalyser.h"
+#include "wavfile.h"
+
+#include <QObject>
+#include <QByteArray>
+#include <QBuffer>
+#include <QVector>
+#include <QtMultimedia/QAudioDeviceInfo>
+#include <QtMultimedia/QAudioFormat>
+
+#ifdef DUMP_CAPTURED_AUDIO
+#define DUMP_DATA
+#endif
+
+#ifdef DUMP_SPECTRUM
+#define DUMP_DATA
+#endif
+
+#ifdef DUMP_DATA
+#include <QDir>
+#endif
+
+class QAudioInput;
+class QAudioOutput;
+class FrequencySpectrum;
+class QFile;
+
+/**
+ * This class interfaces with the QtMultimedia audio classes, and also with
+ * the SpectrumAnalyser class.  Its role is to manage the capture and playback
+ * of audio data, meanwhile performing real-time analysis of the audio level
+ * and frequency spectrum.
+ */
+class Engine : public QObject {
+    Q_OBJECT
+public:
+    Engine(QObject *parent = 0);
+    ~Engine();
+
+    const QList<QAudioDeviceInfo>& availableAudioInputDevices() const
+                                    { return m_availableAudioInputDevices; }
+
+    const QList<QAudioDeviceInfo>& availableAudioOutputDevices() const
+                                    { return m_availableAudioOutputDevices; }
+
+    QAudio::Mode mode() const       { return m_mode; }
+    QAudio::State state() const     { return m_state; }
+
+    /**
+     * \return Reference to internal audio buffer
+     * \note This reference is valid for the lifetime of the Engine
+     */
+    const QByteArray& buffer() const    { return m_buffer; }
+
+    /**
+     * \return Current audio format
+     * \note May be QAudioFormat() if engine is not initialized
+     */
+    const QAudioFormat& format() const  { return m_format; }
+
+    /**
+     * Stop any ongoing recording or playback, and reset to ground state.
+     */
+    void reset();
+
+    /**
+     * Load data from WAV file
+     */
+    bool loadFile(const QString &fileName);
+
+    /**
+     * Generate tone
+     */
+    bool generateTone(const Tone &tone);
+
+    /**
+     * Generate tone
+     */
+    bool generateSweptTone(qreal amplitude);
+
+    /**
+     * Initialize for recording
+     */
+    bool initializeRecord();
+
+    /**
+     * Position of the audio input device.
+     * \return Position in microseconds.
+     */
+    qint64 recordPosition() const   { return m_recordPosition; }
+
+    /**
+     * RMS level of the most recently processed set of audio samples.
+     * \return Level in range (0.0, 1.0)
+     */
+    qreal rmsLevel() const          { return m_rmsLevel; }
+
+    /**
+     * Peak level of the most recently processed set of audio samples.
+     * \return Level in range (0.0, 1.0)
+     */
+    qreal peakLevel() const         { return m_peakLevel; }
+
+    /**
+     * Position of the audio output device.
+     * \return Position in microseconds.
+     */
+    qint64 playPosition() const     { return m_playPosition; }
+
+    /**
+     * Length of the internal engine buffer.
+     * \return Buffer length in microseconds.
+     */
+    qint64 bufferDuration() const;
+
+    /**
+     * Amount of data held in the buffer.
+     * \return Data duration in microseconds.
+     */
+    qint64 dataDuration() const;
+
+    /**
+     * Returns the size of the underlying audio buffer in bytes.
+     * This should be an approximation of the capture latency.
+     */
+    qint64 audioBufferLength() const;
+
+    /**
+     * Set window function applied to audio data before spectral analysis.
+     */
+    void setWindowFunction(WindowFunction type);
+
+public slots:
+    void startRecording();
+    void startPlayback();
+    void suspend();
+    void setAudioInputDevice(const QAudioDeviceInfo &device);
+    void setAudioOutputDevice(const QAudioDeviceInfo &device);
+
+signals:
+    void stateChanged(QAudio::Mode mode, QAudio::State state);
+
+    /**
+     * Informational message for non-modal display
+     */
+    void infoMessage(const QString &message, int durationMs);
+
+    /**
+     * Error message for modal display
+     */
+    void errorMessage(const QString &heading, const QString &detail);
+
+    /**
+     * Format of audio data has changed
+     */
+    void formatChanged(const QAudioFormat &format);
+
+    /**
+     * Length of buffer has changed.
+     * \param duration Duration in microseconds
+     */
+    void bufferDurationChanged(qint64 duration);
+
+    /**
+     * Amount of data in buffer has changed.
+     * \param duration Duration of data in microseconds
+     */
+    void dataDurationChanged(qint64 duration);
+
+    /**
+     * Position of the audio input device has changed.
+     * \param position Position in microseconds
+     */
+    void recordPositionChanged(qint64 position);
+
+    /**
+     * Position of the audio output device has changed.
+     * \param position Position in microseconds
+     */
+    void playPositionChanged(qint64 position);
+
+    /**
+     * Level changed
+     * \param rmsLevel RMS level in range 0.0 - 1.0
+     * \param peakLevel Peak level in range 0.0 - 1.0
+     * \param numSamples Number of audio samples analysed
+     */
+    void levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples);
+
+    /**
+     * Spectrum has changed.
+     * \param position Position of start of window in microseconds
+     * \param length   Length of window in microseconds
+     * \param spectrum Resulting frequency spectrum
+     */
+    void spectrumChanged(qint64 position, qint64 length, const FrequencySpectrum &spectrum);
+
+private slots:
+    void audioNotify();
+    void audioStateChanged(QAudio::State state);
+    void audioDataReady();
+    void spectrumChanged(const FrequencySpectrum &spectrum);
+
+private:
+    bool initialize();
+    bool selectFormat();
+    void stopRecording();
+    void stopPlayback();
+    void setState(QAudio::State state);
+    void setState(QAudio::Mode mode, QAudio::State state);
+    void setFormat(const QAudioFormat &format);
+    void setRecordPosition(qint64 position, bool forceEmit = false);
+    void setPlayPosition(qint64 position, bool forceEmit = false);
+    void calculateLevel(qint64 position, qint64 length);
+    void calculateSpectrum(qint64 position);
+    void setLevel(qreal rmsLevel, qreal peakLevel, int numSamples);
+
+#ifdef DUMP_DATA
+    void createOutputDir();
+    QString outputPath() const { return m_outputDir.path(); }
+#endif
+
+#ifdef DUMP_CAPTURED_AUDIO
+    void dumpData();
+#endif
+
+private:
+    QAudio::Mode        m_mode;
+    QAudio::State       m_state;
+
+    bool                m_generateTone;
+    SweptTone           m_tone;
+
+    QFile*              m_file;
+    WavFile             m_wavFile;
+
+    QAudioFormat        m_format;
+
+    const QList<QAudioDeviceInfo> m_availableAudioInputDevices;
+    QAudioDeviceInfo    m_audioInputDevice;
+    QAudioInput*        m_audioInput;
+    QIODevice*          m_audioInputIODevice;
+    qint64              m_recordPosition;
+
+    const QList<QAudioDeviceInfo> m_availableAudioOutputDevices;
+    QAudioDeviceInfo    m_audioOutputDevice;
+    QAudioOutput*       m_audioOutput;
+    qint64              m_playPosition;
+    QBuffer             m_audioOutputIODevice;
+
+    QByteArray          m_buffer;
+    qint64              m_dataLength;
+
+    qreal               m_rmsLevel;
+    qreal               m_peakLevel;
+
+    int                 m_spectrumLengthBytes;
+    QByteArray          m_spectrumBuffer;
+    SpectrumAnalyser    m_spectrumAnalyser;
+    qint64              m_spectrumPosition;
+
+    int                 m_count;
+
+#ifdef DUMP_DATA
+    QDir                m_outputDir;
+#endif
+
+};
+
+#endif // ENGINE_H