spectrumanalyser.cpp Example File

multimedia/spectrum/app/spectrumanalyser.cpp
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#include "spectrumanalyser.h" #include "utils.h" #include "fftreal_wrapper.h" #include <qmath.h> #include <qmetatype.h> #include <QAudioFormat> #include <QThread> SpectrumAnalyserThread::SpectrumAnalyserThread(QObject *parent) : QObject(parent) #ifndef DISABLE_FFT , m_fft(new FFTRealWrapper) #endif , m_numSamples(SpectrumLengthSamples) , m_windowFunction(DefaultWindowFunction) , m_window(SpectrumLengthSamples, 0.0) , m_input(SpectrumLengthSamples, 0.0) , m_output(SpectrumLengthSamples, 0.0) , m_spectrum(SpectrumLengthSamples) #ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD , m_thread(new QThread(this)) #endif { #ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD // moveToThread() cannot be called on a QObject with a parent setParent(0); moveToThread(m_thread); m_thread->start(); #endif calculateWindow(); } SpectrumAnalyserThread::~SpectrumAnalyserThread() { #ifndef DISABLE_FFT delete m_fft; #endif } void SpectrumAnalyserThread::setWindowFunction(WindowFunction type) { m_windowFunction = type; calculateWindow(); } void SpectrumAnalyserThread::calculateWindow() { for (int i=0; i<m_numSamples; ++i) { DataType x = 0.0; switch (m_windowFunction) { case NoWindow: x = 1.0; break; case HannWindow: x = 0.5 * (1 - qCos((2 * M_PI * i) / (m_numSamples - 1))); break; default: Q_ASSERT(false); } m_window[i] = x; } } void SpectrumAnalyserThread::calculateSpectrum(const QByteArray &buffer, int inputFrequency, int bytesPerSample) { #ifndef DISABLE_FFT Q_ASSERT(buffer.size() == m_numSamples * bytesPerSample); // Initialize data array const char *ptr = buffer.constData(); for (int i=0; i<m_numSamples; ++i) { const qint16 pcmSample = *reinterpret_cast<const qint16*>(ptr); // Scale down to range [-1.0, 1.0] const DataType realSample = pcmToReal(pcmSample); const DataType windowedSample = realSample * m_window[i]; m_input[i] = windowedSample; ptr += bytesPerSample; } // Calculate the FFT m_fft->calculateFFT(m_output.data(), m_input.data()); // Analyze output to obtain amplitude and phase for each frequency for (int i=2; i<=m_numSamples/2; ++i) { // Calculate frequency of this complex sample m_spectrum[i].frequency = qreal(i * inputFrequency) / (m_numSamples); const qreal real = m_output[i]; qreal imag = 0.0; if (i>0 && i<m_numSamples/2) imag = m_output[m_numSamples/2 + i]; const qreal magnitude = qSqrt(real*real + imag*imag); qreal amplitude = SpectrumAnalyserMultiplier * qLn(magnitude); // Bound amplitude to [0.0, 1.0] m_spectrum[i].clipped = (amplitude > 1.0); amplitude = qMax(qreal(0.0), amplitude); amplitude = qMin(qreal(1.0), amplitude); m_spectrum[i].amplitude = amplitude; } #endif emit calculationComplete(m_spectrum); } //============================================================================= // SpectrumAnalyser //============================================================================= SpectrumAnalyser::SpectrumAnalyser(QObject *parent) : QObject(parent) , m_thread(new SpectrumAnalyserThread(this)) , m_state(Idle) #ifdef DUMP_SPECTRUMANALYSER , m_count(0) #endif { connect(m_thread, &SpectrumAnalyserThread::calculationComplete, this, &SpectrumAnalyser::calculationComplete); } SpectrumAnalyser::~SpectrumAnalyser() { } #ifdef DUMP_SPECTRUMANALYSER void SpectrumAnalyser::setOutputPath(const QString &outputDir) { m_outputDir.setPath(outputDir); m_textFile.setFileName(m_outputDir.filePath("spectrum.txt")); m_textFile.open(QIODevice::WriteOnly | QIODevice::Text); m_textStream.setDevice(&m_textFile); } #endif //----------------------------------------------------------------------------- // Public functions //----------------------------------------------------------------------------- void SpectrumAnalyser::setWindowFunction(WindowFunction type) { const bool b = QMetaObject::invokeMethod(m_thread, "setWindowFunction", Qt::AutoConnection, Q_ARG(WindowFunction, type)); Q_ASSERT(b); Q_UNUSED(b) // suppress warnings in release builds } void SpectrumAnalyser::calculate(const QByteArray &buffer, const QAudioFormat &format) { // QThread::currentThread is marked 'for internal use only', but // we're only using it for debug output here, so it's probably OK :) SPECTRUMANALYSER_DEBUG << "SpectrumAnalyser::calculate" << QThread::currentThread() << "state" << m_state; if (isReady()) { Q_ASSERT(isPCMS16LE(format)); const int bytesPerSample = format.sampleSize() * format.channelCount() / 8; #ifdef DUMP_SPECTRUMANALYSER m_count++; const QString pcmFileName = m_outputDir.filePath(QString("spectrum_%1.pcm").arg(m_count, 4, 10, QChar('0'))); QFile pcmFile(pcmFileName); pcmFile.open(QIODevice::WriteOnly); const int bufferLength = m_numSamples * bytesPerSample; pcmFile.write(buffer, bufferLength); m_textStream << "TimeDomain " << m_count << "\n"; const qint16* input = reinterpret_cast<const qint16*>(buffer); for (int i=0; i<m_numSamples; ++i) { m_textStream << i << "\t" << *input << "\n"; input += format.channels(); } #endif m_state = Busy; // Invoke SpectrumAnalyserThread::calculateSpectrum using QMetaObject. If // m_thread is in a different thread from the current thread, the // calculation will be done in the child thread. // Once the calculation is finished, a calculationChanged signal will be // emitted by m_thread. const bool b = QMetaObject::invokeMethod(m_thread, "calculateSpectrum", Qt::AutoConnection, Q_ARG(QByteArray, buffer), Q_ARG(int, format.sampleRate()), Q_ARG(int, bytesPerSample)); Q_ASSERT(b); Q_UNUSED(b) // suppress warnings in release builds #ifdef DUMP_SPECTRUMANALYSER m_textStream << "FrequencySpectrum " << m_count << "\n"; FrequencySpectrum::const_iterator x = m_spectrum.begin(); for (int i=0; i<m_numSamples; ++i, ++x) m_textStream << i << "\t" << x->frequency << "\t" << x->amplitude<< "\t" << x->phase << "\n"; #endif } } bool SpectrumAnalyser::isReady() const { return (Idle == m_state); } void SpectrumAnalyser::cancelCalculation() { if (Busy == m_state) m_state = Cancelled; } //----------------------------------------------------------------------------- // Private slots //----------------------------------------------------------------------------- void SpectrumAnalyser::calculationComplete(const FrequencySpectrum &spectrum) { Q_ASSERT(Idle != m_state); if (Busy == m_state) emit spectrumChanged(spectrum); m_state = Idle; }

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