plugin spectrum analysis: plot A/B

diff --git a/gtk2_ardour/plugin_eq_gui.cc b/gtk2_ardour/plugin_eq_gui.cc
index 2ac9936d35b30d61f1a4e869377dac761152203d..069f3733e1ee4ed72c702b0d41d63a219af756ef 100644 (file)
--- a/gtk2_ardour/plugin_eq_gui.cc
+++ b/gtk2_ardour/plugin_eq_gui.cc
@@ -808,26 +808,19 @@ PluginEqGui::plot_signal_amplitude_difference(Gtk::Widget *w, cairo_t *cr)
        float height = w->get_height();
 
        cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
-       cairo_set_line_width (cr, 2.5);
+       cairo_set_line_width (cr, 1.5);
 
        for (uint32_t i = 0; i < _signal_input_fft->bins()-1; i++) {
                // x coordinate of bin i
                x  = log10f(1.0 + (float)i / (float)_signal_input_fft->bins() * _log_coeff) / _log_max;
                x *= _analysis_width;
 
-               float power_out = power_to_dB(_signal_output_fft->power_at_bin(i));
-               float power_in  = power_to_dB(_signal_input_fft ->power_at_bin(i));
-               float power = power_out - power_in;
+               float power_out = _signal_output_fft->power_at_bin (i) + 1e-30;
+               float power_in  = _signal_input_fft ->power_at_bin (i) + 1e-30;
+               float power = power_to_dB (power_out / power_in);
 
-               if (ISINF(power)) {
-                       if (power < 0) {
-                               power = _min_dB - 1.0;
-                       } else {
-                               power = _max_dB - 1.0;
-                       }
-               } else if (ISNAN(power)) {
-                       power = _min_dB - 1.0;
-               }
+               assert (!ISINF(power));
+               assert (!ISNAN(power));
 
                float yCoeff = ( power - _min_dB) / (_max_dB - _min_dB);