engine.h Example File

multimedia/spectrum/app/engine.h

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  #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