comparison layer/SpectrogramLayer.cpp @ 1127:9fb8dfd7ce4c spectrogram-minor-refactor

Fix threshold in spectrogram -- it wasn't working in the last release.
There is a new protocol for this. Formerly the threshold parameter had a
range from -50dB to 0 with the default at -50, and -50 treated internally
as "no threshold". However, there was a hardcoded, hidden internal threshold
for spectrogram colour mapping at -80dB with anything below this being rounded
to zero. Now the threshold parameter has range -81 to -1 with the default
at -80, -81 is treated internally as "no threshold", and there is no hidden
internal threshold. So the default behaviour is the same as before, an
effective -80dB threshold, but it is now possible to change this in both
directions. Sessions reloaded from prior versions may look slightly different
because, if the session says there should be no threshold, there will now
actually be no threshold instead of having the hidden internal one.

Still need to do something in the UI to make it apparent that the -81dB
setting removes the threshold entirely. This is at least no worse than the
previous, also obscured, magic -50dB setting.

     m_windowSize(1024),
     m_windowType(HanningWindow),
     m_windowHopLevel(2),
     m_gain(1.0),
     m_initialGain(1.0),
-    m_threshold(0.0),
-    m_initialThreshold(0.0),
+    m_threshold(1.0e-8),
+    m_initialThreshold(1.0e-8),
     m_colourRotation(0),
     m_initialRotation(0),
     m_minFrequency(10),
     m_maxFrequency(8000),
     m_initialMaxFrequency(8000),

 	if (val < *min) val = *min;
 	if (val > *max) val = *max;
 
     } else if (name == "Threshold") {
 
-	*min = -50;
-	*max = 0;
+	*min = -81;
+	*max = -1;
 
         *deflt = int(lrint(AudioLevel::multiplier_to_dB(m_initialThreshold)));
 	if (*deflt < *min) *deflt = *min;
 	if (*deflt > *max) *deflt = *max;
 

 {
     if (name == "Gain") {
         return new LinearRangeMapper(-50, 50, -25, 25, tr("dB"));
     }
     if (name == "Threshold") {
-        return new LinearRangeMapper(-50, 0, -50, 0, tr("dB"));
+        return new LinearRangeMapper(-81, -1, -81, -1, tr("dB"));
     }
     return 0;
 }
 
 void
 SpectrogramLayer::setProperty(const PropertyName &name, int value)
 {
     if (name == "Gain") {
 	setGain(float(pow(10, float(value)/20.0)));
     } else if (name == "Threshold") {
-	if (value == -50) setThreshold(0.0);
+	if (value == -81) setThreshold(0.0);
 	else setThreshold(float(AudioLevel::dB_to_multiplier(value)));
     } else if (name == "Colour Rotation") {
 	setColourRotation(value);
     } else if (name == "Colour") {
         setColourMap(value);

 
 	QString top, bottom;
         double min = m_viewMags[v->getId()].getMin();
         double max = m_viewMags[v->getId()].getMax();
 
+        if (min < m_threshold) min = m_threshold;
+        if (max < min) max = min;
+        
         double dBmin = AudioLevel::multiplier_to_dB(min);
         double dBmax = AudioLevel::multiplier_to_dB(max);
 
 #ifdef DEBUG_SPECTROGRAM_REPAINT
         cerr << "paintVerticalScale: for view id " << v->getId()