Qt 5.9 | Qt Multimedia | Spectrum Example | engine.h Example File

Qt 5.9.4 Reference Documentation

# engine.h Example File

multimedia/spectrum/app/engine.h

      /****************************************************************************
      **
      ** Copyright (C) 2017 The Qt Company Ltd.
      ** Contact: https://www.qt.io/licensing/
      **
      ** This file is part of the examples of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
      ** 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 The Qt Company. For licensing terms
      ** and conditions see https://www.qt.io/terms-conditions. For further
      ** information use the contact form at https://www.qt.io/contact-us.
      **
      ** BSD License Usage
      ** Alternatively, 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
      ** 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."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #ifndef ENGINE_H
      #define ENGINE_H

      #include "spectrum.h"
      #include "spectrumanalyser.h"
      #include "wavfile.h"

      #include <QAudioDeviceInfo>
      #include <QAudioFormat>
      #include <QBuffer>
      #include <QByteArray>
      #include <QDir>
      #include <QObject>
      #include <QVector>

      #ifdef DUMP_CAPTURED_AUDIO
      #define DUMP_DATA
      #endif

      #ifdef DUMP_SPECTRUM
      #define DUMP_DATA
      #endif

      class FrequencySpectrum;
      class QAudioInput;
      class QAudioOutput;

      /**
       * This class interfaces with the Qt Multimedia 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:
          explicit 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 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 bytes.
           */
          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 bytes.
           */
          qint64 playPosition() const { return m_playPosition; }

          /**
           * Length of the internal engine buffer.
           * \return Buffer length in bytes.
           */
          qint64 bufferLength() const;

          /**
           * Amount of data held in the buffer.
           * \return Data length in bytes.
           */
          qint64 dataLength() const { return m_dataLength; }

          /**
           * 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 bufferLengthChanged(qint64 duration);

          /**
           * Amount of data in buffer has changed.
           * \param Length of data in bytes
           */
          void dataLengthChanged(qint64 duration);

          /**
           * Position of the audio input device has changed.
           * \param position Position in bytes
           */
          void recordPositionChanged(qint64 position);

          /**
           * Position of the audio output device has changed.
           * \param position Position in bytes
           */
          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 analyzed
           */
          void levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples);

          /**
           * Spectrum has changed.
           * \param position Position of start of window in bytes
           * \param length   Length of window in bytes
           * \param spectrum Resulting frequency spectrum
           */
          void spectrumChanged(qint64 position, qint64 length, const FrequencySpectrum &spectrum);

          /**
           * Buffer containing audio data has changed.
           * \param position Position of start of buffer in bytes
           * \param buffer   Buffer
           */
          void bufferChanged(qint64 position, qint64 length, const QByteArray &buffer);

      private slots:
          void audioNotify();
          void audioStateChanged(QAudio::State state);
          void audioDataReady();
          void spectrumChanged(const FrequencySpectrum &spectrum);

      private:
          void resetAudioDevices();
          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;

          WavFile*            m_file;
          // We need a second file handle via which to read data into m_buffer
          // for analysis
          WavFile*            m_analysisFile;

          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_bufferPosition;
          qint64              m_bufferLength;
          qint64              m_dataLength;

          int                 m_levelBufferLength;
          qreal               m_rmsLevel;
          qreal               m_peakLevel;

          int                 m_spectrumBufferLength;
          QByteArray          m_spectrumBuffer;
          SpectrumAnalyser    m_spectrumAnalyser;
          qint64              m_spectrumPosition;

          int                 m_count;

      #ifdef DUMP_DATA
          QDir                m_outputDir;
      #endif

      };

      #endif // ENGINE_H