engine.cpp Example File

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  #include "engine.h"
  #include "tonegenerator.h"
  #include "utils.h"

  #include <math.h>

  #include <QAudioInput>
  #include <QAudioOutput>
  #include <QCoreApplication>
  #include <QDebug>
  #include <QFile>
  #include <QMetaObject>
  #include <QSet>
  #include <QThread>

  //-----------------------------------------------------------------------------
  // Constants
  //-----------------------------------------------------------------------------

  const qint64 BufferDurationUs       = 10 * 1000000;
  const int    NotifyIntervalMs       = 100;

  // Size of the level calculation window in microseconds
  const int    LevelWindowUs          = 0.1 * 1000000;

  //-----------------------------------------------------------------------------
  // Constructor and destructor
  //-----------------------------------------------------------------------------

  Engine::Engine(QObject *parent)
      :   QObject(parent)
      ,   m_mode(QAudio::AudioInput)
      ,   m_state(QAudio::StoppedState)
      ,   m_generateTone(false)
      ,   m_file(0)
      ,   m_analysisFile(0)
      ,   m_availableAudioInputDevices
              (QAudioDeviceInfo::availableDevices(QAudio::AudioInput))
      ,   m_audioInputDevice(QAudioDeviceInfo::defaultInputDevice())
      ,   m_audioInput(0)
      ,   m_audioInputIODevice(0)
      ,   m_recordPosition(0)
      ,   m_availableAudioOutputDevices
              (QAudioDeviceInfo::availableDevices(QAudio::AudioOutput))
      ,   m_audioOutputDevice(QAudioDeviceInfo::defaultOutputDevice())
      ,   m_audioOutput(0)
      ,   m_playPosition(0)
      ,   m_bufferPosition(0)
      ,   m_bufferLength(0)
      ,   m_dataLength(0)
      ,   m_levelBufferLength(0)
      ,   m_rmsLevel(0.0)
      ,   m_peakLevel(0.0)
      ,   m_spectrumBufferLength(0)
      ,   m_spectrumAnalyser()
      ,   m_spectrumPosition(0)
      ,   m_count(0)
  {
      qRegisterMetaType<FrequencySpectrum>("FrequencySpectrum");
      qRegisterMetaType<WindowFunction>("WindowFunction");
      CHECKED_CONNECT(&m_spectrumAnalyser,
                      SIGNAL(spectrumChanged(FrequencySpectrum)),
                      this,
                      SLOT(spectrumChanged(FrequencySpectrum)));

      initialize();

  #ifdef DUMP_DATA
      createOutputDir();
  #endif

  #ifdef DUMP_SPECTRUM
      m_spectrumAnalyser.setOutputPath(outputPath());
  #endif
  }

  Engine::~Engine()
  {

  }

  //-----------------------------------------------------------------------------
  // Public functions
  //-----------------------------------------------------------------------------

  bool Engine::loadFile(const QString &fileName)
  {
      reset();
      bool result = false;
      Q_ASSERT(!m_generateTone);
      Q_ASSERT(!m_file);
      Q_ASSERT(!fileName.isEmpty());
      m_file = new WavFile(this);
      if (m_file->open(fileName)) {
          if (isPCMS16LE(m_file->fileFormat())) {
              result = initialize();
          } else {
              emit errorMessage(tr("Audio format not supported"),
                                formatToString(m_file->fileFormat()));
          }
      } else {
          emit errorMessage(tr("Could not open file"), fileName);
      }
      if (result) {
          m_analysisFile = new WavFile(this);
          m_analysisFile->open(fileName);
      }
      return result;
  }

  bool Engine::generateTone(const Tone &tone)
  {
      reset();
      Q_ASSERT(!m_generateTone);
      Q_ASSERT(!m_file);
      m_generateTone = true;
      m_tone = tone;
      ENGINE_DEBUG << "Engine::generateTone"
                   << "startFreq" << m_tone.startFreq
                   << "endFreq" << m_tone.endFreq
                   << "amp" << m_tone.amplitude;
      return initialize();
  }

  bool Engine::generateSweptTone(qreal amplitude)
  {
      Q_ASSERT(!m_generateTone);
      Q_ASSERT(!m_file);
      m_generateTone = true;
      m_tone.startFreq = 1;
      m_tone.endFreq = 0;
      m_tone.amplitude = amplitude;
      ENGINE_DEBUG << "Engine::generateSweptTone"
                   << "startFreq" << m_tone.startFreq
                   << "amp" << m_tone.amplitude;
      return initialize();
  }

  bool Engine::initializeRecord()
  {
      reset();
      ENGINE_DEBUG << "Engine::initializeRecord";
      Q_ASSERT(!m_generateTone);
      Q_ASSERT(!m_file);
      m_generateTone = false;
      m_tone = SweptTone();
      return initialize();
  }

  qint64 Engine::bufferLength() const
  {
      return m_file ? m_file->size() : m_bufferLength;
  }

  void Engine::setWindowFunction(WindowFunction type)
  {
      m_spectrumAnalyser.setWindowFunction(type);
  }

  //-----------------------------------------------------------------------------
  // Public slots
  //-----------------------------------------------------------------------------

  void Engine::startRecording()
  {
      if (m_audioInput) {
          if (QAudio::AudioInput == m_mode &&
              QAudio::SuspendedState == m_state) {
              m_audioInput->resume();
          } else {
              m_spectrumAnalyser.cancelCalculation();
              spectrumChanged(0, 0, FrequencySpectrum());

              m_buffer.fill(0);
              setRecordPosition(0, true);
              stopPlayback();
              m_mode = QAudio::AudioInput;
              CHECKED_CONNECT(m_audioInput, SIGNAL(stateChanged(QAudio::State)),
                              this, SLOT(audioStateChanged(QAudio::State)));
              CHECKED_CONNECT(m_audioInput, SIGNAL(notify()),
                              this, SLOT(audioNotify()));
              m_count = 0;
              m_dataLength = 0;
              emit dataLengthChanged(0);
              m_audioInputIODevice = m_audioInput->start();
              CHECKED_CONNECT(m_audioInputIODevice, SIGNAL(readyRead()),
                              this, SLOT(audioDataReady()));
          }
      }
  }

  void Engine::startPlayback()
  {
      if (m_audioOutput) {
          if (QAudio::AudioOutput == m_mode &&
              QAudio::SuspendedState == m_state) {
  #ifdef Q_OS_WIN
              // The Windows backend seems to internally go back into ActiveState
              // while still returning SuspendedState, so to ensure that it doesn't
              // ignore the resume() call, we first re-suspend
              m_audioOutput->suspend();
  #endif
              m_audioOutput->resume();
          } else {
              m_spectrumAnalyser.cancelCalculation();
              spectrumChanged(0, 0, FrequencySpectrum());
              setPlayPosition(0, true);
              stopRecording();
              m_mode = QAudio::AudioOutput;
              CHECKED_CONNECT(m_audioOutput, SIGNAL(stateChanged(QAudio::State)),
                              this, SLOT(audioStateChanged(QAudio::State)));
              CHECKED_CONNECT(m_audioOutput, SIGNAL(notify()),
                              this, SLOT(audioNotify()));
              m_count = 0;
              if (m_file) {
                  m_file->seek(0);
                  m_bufferPosition = 0;
                  m_dataLength = 0;
                  m_audioOutput->start(m_file);
              } else {
                  m_audioOutputIODevice.close();
                  m_audioOutputIODevice.setBuffer(&m_buffer);
                  m_audioOutputIODevice.open(QIODevice::ReadOnly);
                  m_audioOutput->start(&m_audioOutputIODevice);
              }
          }
      }
  }

  void Engine::suspend()
  {
      if (QAudio::ActiveState == m_state ||
          QAudio::IdleState == m_state) {
          switch (m_mode) {
          case QAudio::AudioInput:
              m_audioInput->suspend();
              break;
          case QAudio::AudioOutput:
              m_audioOutput->suspend();
              break;
          }
      }
  }

  void Engine::setAudioInputDevice(const QAudioDeviceInfo &device)
  {
      if (device.deviceName() != m_audioInputDevice.deviceName()) {
          m_audioInputDevice = device;
          initialize();
      }
  }

  void Engine::setAudioOutputDevice(const QAudioDeviceInfo &device)
  {
      if (device.deviceName() != m_audioOutputDevice.deviceName()) {
          m_audioOutputDevice = device;
          initialize();
      }
  }

  //-----------------------------------------------------------------------------
  // Private slots
  //-----------------------------------------------------------------------------

  void Engine::audioNotify()
  {
      switch (m_mode) {
      case QAudio::AudioInput: {
              const qint64 recordPosition = qMin(m_bufferLength, audioLength(m_format, m_audioInput->processedUSecs()));
              setRecordPosition(recordPosition);
              const qint64 levelPosition = m_dataLength - m_levelBufferLength;
              if (levelPosition >= 0)
                  calculateLevel(levelPosition, m_levelBufferLength);
              if (m_dataLength >= m_spectrumBufferLength) {
                  const qint64 spectrumPosition = m_dataLength - m_spectrumBufferLength;
                  calculateSpectrum(spectrumPosition);
              }
              emit bufferChanged(0, m_dataLength, m_buffer);
          }
          break;
      case QAudio::AudioOutput: {
              const qint64 playPosition = audioLength(m_format, m_audioOutput->processedUSecs());
              setPlayPosition(qMin(bufferLength(), playPosition));
              const qint64 levelPosition = playPosition - m_levelBufferLength;
              const qint64 spectrumPosition = playPosition - m_spectrumBufferLength;
              if (m_file) {
                  if (levelPosition > m_bufferPosition ||
                      spectrumPosition > m_bufferPosition ||
                      qMax(m_levelBufferLength, m_spectrumBufferLength) > m_dataLength) {
                      m_bufferPosition = 0;
                      m_dataLength = 0;
                      // Data needs to be read into m_buffer in order to be analysed
                      const qint64 readPos = qMax(qint64(0), qMin(levelPosition, spectrumPosition));
                      const qint64 readEnd = qMin(m_analysisFile->size(), qMax(levelPosition + m_levelBufferLength, spectrumPosition + m_spectrumBufferLength));
                      const qint64 readLen = readEnd - readPos + audioLength(m_format, WaveformWindowDuration);
                      qDebug() << "Engine::audioNotify [1]"
                               << "analysisFileSize" << m_analysisFile->size()
                               << "readPos" << readPos
                               << "readLen" << readLen;
                      if (m_analysisFile->seek(readPos + m_analysisFile->headerLength())) {
                          m_buffer.resize(readLen);
                          m_bufferPosition = readPos;
                          m_dataLength = m_analysisFile->read(m_buffer.data(), readLen);
                          qDebug() << "Engine::audioNotify [2]" << "bufferPosition" << m_bufferPosition << "dataLength" << m_dataLength;
                      } else {
                          qDebug() << "Engine::audioNotify [2]" << "file seek error";
                      }
                      emit bufferChanged(m_bufferPosition, m_dataLength, m_buffer);
                  }
              } else {
                  if (playPosition >= m_dataLength)
                      stopPlayback();
              }
              if (levelPosition >= 0 && levelPosition + m_levelBufferLength < m_bufferPosition + m_dataLength)
                  calculateLevel(levelPosition, m_levelBufferLength);
              if (spectrumPosition >= 0 && spectrumPosition + m_spectrumBufferLength < m_bufferPosition + m_dataLength)
                  calculateSpectrum(spectrumPosition);
          }
          break;
      }
  }

  void Engine::audioStateChanged(QAudio::State state)
  {
      ENGINE_DEBUG << "Engine::audioStateChanged from" << m_state
                   << "to" << state;

      if (QAudio::IdleState == state && m_file && m_file->pos() == m_file->size()) {
          stopPlayback();
      } else {
          if (QAudio::StoppedState == state) {
              // Check error
              QAudio::Error error = QAudio::NoError;
              switch (m_mode) {
              case QAudio::AudioInput:
                  error = m_audioInput->error();
                  break;
              case QAudio::AudioOutput:
                  error = m_audioOutput->error();
                  break;
              }
              if (QAudio::NoError != error) {
                  reset();
                  return;
              }
          }
          setState(state);
      }
  }

  void Engine::audioDataReady()
  {
      Q_ASSERT(0 == m_bufferPosition);
      const qint64 bytesReady = m_audioInput->bytesReady();
      const qint64 bytesSpace = m_buffer.size() - m_dataLength;
      const qint64 bytesToRead = qMin(bytesReady, bytesSpace);

      const qint64 bytesRead = m_audioInputIODevice->read(
                                         m_buffer.data() + m_dataLength,
                                         bytesToRead);

      if (bytesRead) {
          m_dataLength += bytesRead;
          emit dataLengthChanged(dataLength());
      }

      if (m_buffer.size() == m_dataLength)
          stopRecording();
  }

  void Engine::spectrumChanged(const FrequencySpectrum &spectrum)
  {
      ENGINE_DEBUG << "Engine::spectrumChanged" << "pos" << m_spectrumPosition;
      emit spectrumChanged(m_spectrumPosition, m_spectrumBufferLength, spectrum);
  }

  //-----------------------------------------------------------------------------
  // Private functions
  //-----------------------------------------------------------------------------

  void Engine::resetAudioDevices()
  {
      delete m_audioInput;
      m_audioInput = 0;
      m_audioInputIODevice = 0;
      setRecordPosition(0);
      delete m_audioOutput;
      m_audioOutput = 0;
      setPlayPosition(0);
      m_spectrumPosition = 0;
      setLevel(0.0, 0.0, 0);
  }

  void Engine::reset()
  {
      stopRecording();
      stopPlayback();
      setState(QAudio::AudioInput, QAudio::StoppedState);
      setFormat(QAudioFormat());
      m_generateTone = false;
      delete m_file;
      m_file = 0;
      delete m_analysisFile;
      m_analysisFile = 0;
      m_buffer.clear();
      m_bufferPosition = 0;
      m_bufferLength = 0;
      m_dataLength = 0;
      emit dataLengthChanged(0);
      resetAudioDevices();
  }

  bool Engine::initialize()
  {
      bool result = false;

      QAudioFormat format = m_format;

      if (selectFormat()) {
          if (m_format != format) {
              resetAudioDevices();
              if (m_file) {
                  emit bufferLengthChanged(bufferLength());
                  emit dataLengthChanged(dataLength());
                  emit bufferChanged(0, 0, m_buffer);
                  setRecordPosition(bufferLength());
                  result = true;
              } else {
                  m_bufferLength = audioLength(m_format, BufferDurationUs);
                  m_buffer.resize(m_bufferLength);
                  m_buffer.fill(0);
                  emit bufferLengthChanged(bufferLength());
                  if (m_generateTone) {
                      if (0 == m_tone.endFreq) {
                          const qreal nyquist = nyquistFrequency(m_format);
                          m_tone.endFreq = qMin(qreal(SpectrumHighFreq), nyquist);
                      }
                      // Call function defined in utils.h, at global scope
                      ::generateTone(m_tone, m_format, m_buffer);
                      m_dataLength = m_bufferLength;
                      emit dataLengthChanged(dataLength());
                      emit bufferChanged(0, m_dataLength, m_buffer);
                      setRecordPosition(m_bufferLength);
                      result = true;
                  } else {
                      emit bufferChanged(0, 0, m_buffer);
                      m_audioInput = new QAudioInput(m_audioInputDevice, m_format, this);
                      m_audioInput->setNotifyInterval(NotifyIntervalMs);
                      result = true;
                  }
              }
              m_audioOutput = new QAudioOutput(m_audioOutputDevice, m_format, this);
              m_audioOutput->setNotifyInterval(NotifyIntervalMs);
          }
      } else {
          if (m_file)
              emit errorMessage(tr("Audio format not supported"),
                                formatToString(m_format));
          else if (m_generateTone)
              emit errorMessage(tr("No suitable format found"), "");
          else
              emit errorMessage(tr("No common input / output format found"), "");
      }

      ENGINE_DEBUG << "Engine::initialize" << "m_bufferLength" << m_bufferLength;
      ENGINE_DEBUG << "Engine::initialize" << "m_dataLength" << m_dataLength;
      ENGINE_DEBUG << "Engine::initialize" << "format" << m_format;

      return result;
  }

  bool Engine::selectFormat()
  {
      bool foundSupportedFormat = false;

      if (m_file || QAudioFormat() != m_format) {
          QAudioFormat format = m_format;
          if (m_file)
              // Header is read from the WAV file; just need to check whether
              // it is supported by the audio output device
              format = m_file->fileFormat();
          if (m_audioOutputDevice.isFormatSupported(format)) {
              setFormat(format);
              foundSupportedFormat = true;
          }
      } else {

          QList<int> sampleRatesList;
      #ifdef Q_OS_WIN
          // The Windows audio backend does not correctly report format support
          // (see QTBUG-9100).  Furthermore, although the audio subsystem captures
          // at 11025Hz, the resulting audio is corrupted.
          sampleRatesList += 8000;
      #endif

          if (!m_generateTone)
              sampleRatesList += m_audioInputDevice.supportedSampleRates();

          sampleRatesList += m_audioOutputDevice.supportedSampleRates();
          sampleRatesList = sampleRatesList.toSet().toList(); // remove duplicates
          qSort(sampleRatesList);
          ENGINE_DEBUG << "Engine::initialize frequenciesList" << sampleRatesList;

          QList<int> channelsList;
          channelsList += m_audioInputDevice.supportedChannelCounts();
          channelsList += m_audioOutputDevice.supportedChannelCounts();
          channelsList = channelsList.toSet().toList();
          qSort(channelsList);
          ENGINE_DEBUG << "Engine::initialize channelsList" << channelsList;

          QAudioFormat format;
          format.setByteOrder(QAudioFormat::LittleEndian);
          format.setCodec("audio/pcm");
          format.setSampleSize(16);
          format.setSampleType(QAudioFormat::SignedInt);
          int sampleRate, channels;
          foreach (sampleRate, sampleRatesList) {
              if (foundSupportedFormat)
                  break;
              format.setSampleRate(sampleRate);
              foreach (channels, channelsList) {
                  format.setChannelCount(channels);
                  const bool inputSupport = m_generateTone ||
                                            m_audioInputDevice.isFormatSupported(format);
                  const bool outputSupport = m_audioOutputDevice.isFormatSupported(format);
                  ENGINE_DEBUG << "Engine::initialize checking " << format
                               << "input" << inputSupport
                               << "output" << outputSupport;
                  if (inputSupport && outputSupport) {
                      foundSupportedFormat = true;
                      break;
                  }
              }
          }

          if (!foundSupportedFormat)
              format = QAudioFormat();

          setFormat(format);
      }

      return foundSupportedFormat;
  }

  void Engine::stopRecording()
  {
      if (m_audioInput) {
          m_audioInput->stop();
          QCoreApplication::instance()->processEvents();
          m_audioInput->disconnect();
      }
      m_audioInputIODevice = 0;

  #ifdef DUMP_AUDIO
      dumpData();
  #endif
  }

  void Engine::stopPlayback()
  {
      if (m_audioOutput) {
          m_audioOutput->stop();
          QCoreApplication::instance()->processEvents();
          m_audioOutput->disconnect();
          setPlayPosition(0);
      }
  }

  void Engine::setState(QAudio::State state)
  {
      const bool changed = (m_state != state);
      m_state = state;
      if (changed)
          emit stateChanged(m_mode, m_state);
  }

  void Engine::setState(QAudio::Mode mode, QAudio::State state)
  {
      const bool changed = (m_mode != mode || m_state != state);
      m_mode = mode;
      m_state = state;
      if (changed)
          emit stateChanged(m_mode, m_state);
  }

  void Engine::setRecordPosition(qint64 position, bool forceEmit)
  {
      const bool changed = (m_recordPosition != position);
      m_recordPosition = position;
      if (changed || forceEmit)
          emit recordPositionChanged(m_recordPosition);
  }

  void Engine::setPlayPosition(qint64 position, bool forceEmit)
  {
      const bool changed = (m_playPosition != position);
      m_playPosition = position;
      if (changed || forceEmit)
          emit playPositionChanged(m_playPosition);
  }

  void Engine::calculateLevel(qint64 position, qint64 length)
  {
  #ifdef DISABLE_LEVEL
      Q_UNUSED(position)
      Q_UNUSED(length)
  #else
      Q_ASSERT(position + length <= m_bufferPosition + m_dataLength);

      qreal peakLevel = 0.0;

      qreal sum = 0.0;
      const char *ptr = m_buffer.constData() + position - m_bufferPosition;
      const char *const end = ptr + length;
      while (ptr < end) {
          const qint16 value = *reinterpret_cast<const qint16*>(ptr);
          const qreal fracValue = pcmToReal(value);
          peakLevel = qMax(peakLevel, fracValue);
          sum += fracValue * fracValue;
          ptr += 2;
      }
      const int numSamples = length / 2;
      qreal rmsLevel = sqrt(sum / numSamples);

      rmsLevel = qMax(qreal(0.0), rmsLevel);
      rmsLevel = qMin(qreal(1.0), rmsLevel);
      setLevel(rmsLevel, peakLevel, numSamples);

      ENGINE_DEBUG << "Engine::calculateLevel" << "pos" << position << "len" << length
                   << "rms" << rmsLevel << "peak" << peakLevel;
  #endif
  }

  void Engine::calculateSpectrum(qint64 position)
  {
  #ifdef DISABLE_SPECTRUM
      Q_UNUSED(position)
  #else
      Q_ASSERT(position + m_spectrumBufferLength <= m_bufferPosition + m_dataLength);
      Q_ASSERT(0 == m_spectrumBufferLength % 2); // constraint of FFT algorithm

      // QThread::currentThread is marked 'for internal use only', but
      // we're only using it for debug output here, so it's probably OK :)
      ENGINE_DEBUG << "Engine::calculateSpectrum" << QThread::currentThread()
                   << "count" << m_count << "pos" << position << "len" << m_spectrumBufferLength
                   << "spectrumAnalyser.isReady" << m_spectrumAnalyser.isReady();

      if (m_spectrumAnalyser.isReady()) {
          m_spectrumBuffer = QByteArray::fromRawData(m_buffer.constData() + position - m_bufferPosition,
                                                     m_spectrumBufferLength);
          m_spectrumPosition = position;
          m_spectrumAnalyser.calculate(m_spectrumBuffer, m_format);
      }
  #endif
  }

  void Engine::setFormat(const QAudioFormat &format)
  {
      const bool changed = (format != m_format);
      m_format = format;
      m_levelBufferLength = audioLength(m_format, LevelWindowUs);
      m_spectrumBufferLength = SpectrumLengthSamples *
                              (m_format.sampleSize() / 8) * m_format.channelCount();
      if (changed)
          emit formatChanged(m_format);
  }

  void Engine::setLevel(qreal rmsLevel, qreal peakLevel, int numSamples)
  {
      m_rmsLevel = rmsLevel;
      m_peakLevel = peakLevel;
      emit levelChanged(m_rmsLevel, m_peakLevel, numSamples);
  }

  #ifdef DUMP_DATA
  void Engine::createOutputDir()
  {
      m_outputDir.setPath("output");

      // Ensure output directory exists and is empty
      if (m_outputDir.exists()) {
          const QStringList files = m_outputDir.entryList(QDir::Files);
          QString file;
          foreach (file, files)
              m_outputDir.remove(file);
      } else {
          QDir::current().mkdir("output");
      }
  }
  #endif // DUMP_DATA

  #ifdef DUMP_AUDIO
  void Engine::dumpData()
  {
      const QString txtFileName = m_outputDir.filePath("data.txt");
      QFile txtFile(txtFileName);
      txtFile.open(QFile::WriteOnly | QFile::Text);
      QTextStream stream(&txtFile);
      const qint16 *ptr = reinterpret_cast<const qint16*>(m_buffer.constData());
      const int numSamples = m_dataLength / (2 * m_format.channels());
      for (int i=0; i<numSamples; ++i) {
          stream << i << "\t" << *ptr << "\n";
          ptr += m_format.channels();
      }

      const QString pcmFileName = m_outputDir.filePath("data.pcm");
      QFile pcmFile(pcmFileName);
      pcmFile.open(QFile::WriteOnly);
      pcmFile.write(m_buffer.constData(), m_dataLength);
  }
  #endif // DUMP_AUDIO