Added a time resolution slider

mainwindow.cpp

@@ -46,6 +46,8 @@ MainWindow::MainWindow()
     connect(dock, SIGNAL(fftOrZoomChanged(int, int)), plots, SLOT(setFFTAndZoom(int, int)));
     connect(dock->powerMaxSlider, SIGNAL(valueChanged(int)), plots, SLOT(setPowerMax(int)));
     connect(dock->powerMinSlider, SIGNAL(valueChanged(int)), plots, SLOT(setPowerMin(int)));
+    connect(dock->timeResolutionSlider, SIGNAL(valueChanged(int)), plots, SLOT(setTimeResolution(int)));
+    connect(dock->betaSlider, SIGNAL(valueChanged(int)), plots, SLOT(setBeta(int)));
     connect(dock->cursorsCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableCursors);
     connect(dock->scalesCheckBox, &QCheckBox::stateChanged, plots, &PlotView::enableScales);
     connect(dock->cursorSymbolsSpinBox, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), plots, &PlotView::setCursorSegments);

plotview.cpp

@@ -382,7 +382,7 @@ void PlotView::setFFTAndZoom(int size, int zoom)
 
 void PlotView::setPowerMin(int power)
 {
-    powerMin = power;
+   powerMin = power;
     if (spectrogramPlot != nullptr)
         spectrogramPlot->setPowerMin(power);
     updateView();
@@ -396,6 +396,18 @@ void PlotView::setPowerMax(int power)
     updateView();
 }
 
+void PlotView::setTimeResolution(int resolution)
+{
+    if (spectrogramPlot != nullptr)
+        spectrogramPlot->setTimeResolution(resolution);
+}
+
+void PlotView::setBeta(int beta)
+{
+    if (spectrogramPlot != nullptr)
+        spectrogramPlot->setBeta(beta);
+}
+
 void PlotView::paintEvent(QPaintEvent *event)
 {
     if (mainSampleSource == nullptr) return;

plotview.h

@@ -52,6 +52,8 @@ public slots:
     void setFFTAndZoom(int fftSize, int zoomLevel);
     void setPowerMin(int power);
     void setPowerMax(int power);
+    void setTimeResolution(int resolution);
+    void setBeta(int beta);
 
 protected:
     void contextMenuEvent(QContextMenuEvent * event) override;

spectrogramcontrols.cpp

@@ -55,6 +55,14 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
 
     layout->addRow(new QLabel(tr("Zoom:")), zoomLevelSlider);
 
+    timeResolutionSlider = new QSlider(Qt::Horizontal, widget);
+    timeResolutionSlider->setRange(0, 99);
+    layout->addRow(new QLabel(tr("Time resolution:")), timeResolutionSlider);
+
+    betaSlider = new QSlider(Qt::Horizontal, widget);
+    betaSlider->setRange(0, 15);
+    layout->addRow(new QLabel(tr("Beta:")), betaSlider);
+
     powerMaxSlider = new QSlider(Qt::Horizontal, widget);
     powerMaxSlider->setRange(-140, 10);
     layout->addRow(new QLabel(tr("Power max:")), powerMaxSlider);

spectrogramcontrols.h

@@ -66,6 +66,8 @@ private slots:
     QSlider *zoomLevelSlider;
     QSlider *powerMaxSlider;
     QSlider *powerMinSlider;
+    QSlider *timeResolutionSlider;
+    QSlider *betaSlider;
     QCheckBox *cursorsCheckBox;
     QSpinBox *cursorSymbolsSpinBox;
     QLabel *rateLabel;

spectrogramplot.cpp

@@ -33,12 +33,14 @@
 
 SpectrogramPlot::SpectrogramPlot(std::shared_ptr<SampleSource<std::complex<float>>> src) : Plot(src), inputSource(src), fftSize(512), tuner(fftSize, this)
 {
-    setFFTSize(fftSize);
     zoomLevel = 1;
     powerMax = 0.0f;
     powerMin = -50.0f;
+    timeResolution = 0.0;
     sampleRate = 0;
+    beta = 4.0;
     frequencyScaleEnabled = false;
+    setFFTSize(fftSize);
 
     for (int i = 0; i < 256; i++) {
         float p = (float)i / 256;
@@ -274,12 +276,29 @@ std::shared_ptr<AbstractSampleSource> SpectrogramPlot::output()
 void SpectrogramPlot::setFFTSize(int size)
 {
     float sizeScale = float(size) / float(fftSize);
+
     fftSize = size;
     fft.reset(new FFT(fftSize));
 
     window.reset(new float[fftSize]);
-    for (int i = 0; i < fftSize; i++) {
-        window[i] = 0.5f * (1.0f - cos(Tau * i / (fftSize - 1)));
+    int zeroCount = (fftSize * timeResolution) / 100;
+    if ((zeroCount >= 0) && (zeroCount <= fftSize)) {
+        int windowSize = fftSize - zeroCount;
+        int leadingZeroCount = zeroCount/2;
+
+        for (int i = 0; i < leadingZeroCount; i++) {
+            window[i] = 0;
+        }
+        for (int i = 0; i < windowSize; i++) {
+            window[i + leadingZeroCount] = kaiser(i, windowSize, beta, 0.0);
+        }
+        for (int i = windowSize + leadingZeroCount; i < fftSize; i++) {
+            window[i] = 0;
+        }
+    } else {
+        for(int i = 0; i < fftSize; i++) {
+            window[i] = 0;
+        }
     }
 
     setHeight(fftSize);
@@ -303,6 +322,19 @@ void SpectrogramPlot::setPowerMin(int power)
     pixmapCache.clear();
 }
 
+void SpectrogramPlot::setTimeResolution(int resolution)
+{
+    timeResolution = resolution;
+    setFFTSize(fftSize);
+    invalidateEvent();
+}
+
+void SpectrogramPlot::setBeta(float beta)
+{
+    this->beta = beta;
+    setFFTSize(fftSize);
+    invalidateEvent();
+}
 void SpectrogramPlot::setZoomLevel(int zoom)
 {
     zoomLevel = zoom;

spectrogramplot.h

@@ -54,6 +54,8 @@ public slots:
     void setPowerMax(int power);
     void setPowerMin(int power);
     void setZoomLevel(int zoom);
+    void setTimeResolution(int res);
+    void setBeta(float beta);
     void tunerMoved();
 
 private:
@@ -71,6 +73,8 @@ public slots:
     int zoomLevel;
     float powerMax;
     float powerMin;
+    int timeResolution;
+    float beta;
     off_t sampleRate;
     bool frequencyScaleEnabled;