Spectrum: use common constants for FFT size limits and set limits to 64 to 8k

sdrbase/dsp/spectrumsettings.h

@@ -63,6 +63,8 @@ public:
     bool m_usb;    //!< USB display with increasing frequencies towads the right - else decreasing frequencies
     QString m_wsSpectrumAddress;
     uint16_t m_wsSpectrumPort;
+	static const int m_log2FFTSizeMin = 6;   // 64
+	static const int m_log2FFTSizeMax = 13;  // 8k
 
     SpectrumSettings();
 	virtual ~SpectrumSettings();

sdrbase/dsp/spectrumvis.cpp

@@ -30,8 +30,6 @@
 
 #include "spectrumvis.h"
 
-#define MAX_FFT_SIZE 4096
-
 #ifndef LINUX
 inline double log2(double n)
 {
@@ -53,9 +51,9 @@ SpectrumVis::SpectrumVis(Real scalef) :
     m_running(true),
 	m_fft(nullptr),
     m_fftEngineSequence(0),
-	m_fftBuffer(MAX_FFT_SIZE),
-	m_powerSpectrum(MAX_FFT_SIZE),
-    m_psd(MAX_FFT_SIZE),
+	m_fftBuffer(4096),
+	m_powerSpectrum(4096),
+    m_psd(4096),
 	m_fftBufferFill(0),
 	m_needMoreSamples(false),
     m_frequencyZoomFactor(1.0f),
@@ -774,10 +772,10 @@ void SpectrumVis::applySettings(const SpectrumSettings& settings, bool force)
 {
     QMutexLocker mutexLocker(&m_mutex);
 
-    int fftSize = settings.m_fftSize > MAX_FFT_SIZE ?
-        MAX_FFT_SIZE :
-        settings.m_fftSize < 64 ?
-            64 :
+    int fftSize = settings.m_fftSize > (1<<SpectrumSettings::m_log2FFTSizeMax) ?
+        (1<<SpectrumSettings::m_log2FFTSizeMax) :
+        settings.m_fftSize < (1<<SpectrumSettings::m_log2FFTSizeMin) ?
+            (1<<SpectrumSettings::m_log2FFTSizeMin) :
             settings.m_fftSize;
 
     qDebug() << "SpectrumVis::applySettings:"
@@ -808,6 +806,13 @@ void SpectrumVis::applySettings(const SpectrumSettings& settings, bool force)
         m_fftEngineSequence = fftFactory->getEngine(fftSize, false, &m_fft);
         m_ofs = 20.0f * log10f(1.0f / fftSize);
         m_powFFTDiv = fftSize * fftSize;
+
+        if (fftSize > m_settings.m_fftSize)
+        {
+            m_fftBuffer.resize(fftSize);
+            m_powerSpectrum.resize(fftSize);
+            m_psd.resize(fftSize);
+        }
     }
 
     if ((fftSize != m_settings.m_fftSize)

sdrgui/gui/glspectrumgui.cpp

@@ -138,11 +138,11 @@ void GLSpectrumGUI::displaySettings()
 
 	ui->fftWindow->setCurrentIndex(m_settings.m_fftWindow);
 
-	for (int i = 0; i < 6; i++)
+	for (int i = SpectrumSettings::m_log2FFTSizeMin; i <= SpectrumSettings::m_log2FFTSizeMax; i++)
 	{
-		if (m_settings.m_fftSize == (1 << (i + 7)))
+		if (m_settings.m_fftSize == (1 << i))
 		{
-			ui->fftSize->setCurrentIndex(i);
+			ui->fftSize->setCurrentIndex(i - SpectrumSettings::m_log2FFTSizeMin);
 			break;
 		}
 	}
@@ -236,7 +236,7 @@ void GLSpectrumGUI::on_fftWindow_currentIndexChanged(int index)
 void GLSpectrumGUI::on_fftSize_currentIndexChanged(int index)
 {
 	qDebug("GLSpectrumGUI::on_fftSize_currentIndexChanged: %d", index);
-	m_settings.m_fftSize = 1 << (7 + index);
+	m_settings.m_fftSize = 1 << (SpectrumSettings::m_log2FFTSizeMin + index);
     setMaximumOverlap();
 	applySettings();
 	setAveragingToolitp();
@@ -576,7 +576,13 @@ void GLSpectrumGUI::setAveragingToolitp()
 
 void GLSpectrumGUI::setFFTSize(int log2FFTSize)
 {
-    ui->fftSize->setCurrentIndex(log2FFTSize < 7 ? 0 : log2FFTSize > 12 ? 5 : log2FFTSize - 7); // 128 to 4096 in powers of 2
+    ui->fftSize->setCurrentIndex(
+        log2FFTSize < SpectrumSettings::m_log2FFTSizeMin ?
+            0
+            : log2FFTSize > SpectrumSettings::m_log2FFTSizeMax ?
+                SpectrumSettings::m_log2FFTSizeMax - SpectrumSettings::m_log2FFTSizeMin
+                : log2FFTSize - SpectrumSettings::m_log2FFTSizeMin
+    );
 }
 
 void GLSpectrumGUI::setMaximumOverlap()

sdrgui/gui/glspectrumgui.ui

@@ -129,6 +129,11 @@
        <property name="sizeAdjustPolicy">
         <enum>QComboBox::AdjustToContents</enum>
        </property>
+       <item>
+        <property name="text">
+         <string>64</string>
+        </property>
+       </item>
        <item>
         <property name="text">
          <string>128</string>
@@ -159,6 +164,11 @@
          <string>4k</string>
         </property>
        </item>
+       <item>
+        <property name="text">
+         <string>8k</string>
+        </property>
+       </item>
       </widget>
      </item>
      <item>