use fixed fall-off time for k-meter

diff --git a/libs/ardour/meter.cc b/libs/ardour/meter.cc
index 32c7439fd52525af49d293820b0c90ac6cea1220..cc014caf630f6626be9ca8c0d9fa282830e151bf 100644 (file)
--- a/libs/ardour/meter.cc
+++ b/libs/ardour/meter.cc
@@ -273,6 +273,11 @@ PeakMeter::meter ()
        const size_t limit = min (_peak_signal.size(), (size_t) current_meters.n_total ());
        const size_t n_midi  = min (_peak_signal.size(), (size_t) current_meters.n_midi());
 
+       /* 0.01f ^= 100 Hz update rate */
+       const float midi_meter_falloff = Config->get_meter_falloff() * 0.01f;
+       /* kmeters: 24dB / 2 sec */
+       const float audio_meter_falloff = (_meter_type & (MeterK20 | MeterK14)) ? 0.12f : midi_meter_falloff;
+
        for (size_t n = 0; n < limit; ++n) {
 
                /* grab peak since last read */
@@ -283,11 +288,11 @@ PeakMeter::meter ()
                if (n < n_midi) {
                        _max_peak_power[n] = -INFINITY; // std::max (new_peak, _max_peak_power[n]); // XXX
                        _max_peak_signal[n] = 0;
-                       if (Config->get_meter_falloff() == 0.0f || new_peak > _visible_peak_power[n]) {
+                       if (midi_meter_falloff == 0.0f || new_peak > _visible_peak_power[n]) {
                                ;
                        } else {
-                               /* empirical WRT to falloff times , 0.01f ^= 100 Hz update rate */
-                               new_peak = _visible_peak_power[n] - sqrt(_visible_peak_power[n] * Config->get_meter_falloff() * 0.01f * 0.0002f);
+                               /* empirical algorithm WRT to audio falloff times */
+                               new_peak = _visible_peak_power[n] - sqrt(_visible_peak_power[n] * midi_meter_falloff * 0.0002f);
                                if (new_peak < (1.0 / 512.0)) new_peak = 0;
                        }
                        _visible_peak_power[n] = new_peak;
@@ -310,11 +315,11 @@ PeakMeter::meter ()
 
                _max_peak_power[n] = std::max (new_peak, _max_peak_power[n]);
 
-               if (Config->get_meter_falloff() == 0.0f || new_peak > _visible_peak_power[n]) {
+               if (audio_meter_falloff == 0.0f || new_peak > _visible_peak_power[n]) {
                        _visible_peak_power[n] = new_peak;
                } else {
                        // do falloff
-                       new_peak = _visible_peak_power[n] - (Config->get_meter_falloff() * 0.01f);
+                       new_peak = _visible_peak_power[n] - (audio_meter_falloff);
                        _visible_peak_power[n] = std::max (new_peak, -INFINITY);
                }
        }