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/****************************************************************************
**
** Copyright (C) 2014 Digia Plc
** All rights reserved.
** For any questions to Digia, please use contact form at http://qt.io
**
** This file is part of the Qt Data Visualization module.
**
** Licensees holding valid commercial license for Qt may use this file in
** accordance with the Qt License Agreement provided with the Software
** or, alternatively, in accordance with the terms contained in a written
** agreement between you and Digia.
**
** If you have questions regarding the use of this file, please use
** contact form at http://qt.io
**
****************************************************************************/
#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),
m_fft(new FFTRealWrapper),
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()
{
delete m_fft;
}
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)
{
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 = sqrt(real*real + imag*imag);
qreal amplitude = SpectrumAnalyserMultiplier * log(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;
}
emit calculationComplete(m_spectrum);
}
//=============================================================================
// SpectrumAnalyser
//=============================================================================
SpectrumAnalyser::SpectrumAnalyser(QObject *parent)
: QObject(parent),
m_thread(new SpectrumAnalyserThread(this)),
m_state(Idle)
{
CHECKED_CONNECT(m_thread, SIGNAL(calculationComplete(FrequencySpectrum)),
this, SLOT(calculationComplete(FrequencySpectrum)));
}
SpectrumAnalyser::~SpectrumAnalyser()
{
}
//-----------------------------------------------------------------------------
// 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;
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
}
}
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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